today marks the most deadly shooting in american history. this was an act of terror and an act of hate. >> my son was in the club when his boyfriend ron got shot multiple times. >> people on the ground bleeding, people screaming. >> i could just smell the ammo in the air. i was like this is a gun, this isn't fireworks, we need to leave.

>> the suspect's name is omar mateen, he lives in port st. lucie. >> something really horrible happened that happened to all of us. >> as americans, we are united in grief and outrage. >> you will not break us. we are better people than this. >> good evening from orlando. i'm lester holt and this is a special edition of "dateline." at least 50 dead, 53 wounded, many of them in critical condition. the biggest mass shooting in american history, and says president obama. an act of terror. the gunman omar mateen, stormed a gay nightclub, armed with an assault style military nightclub, opened fire and left the dance floor covered in blood.

his motive, pure rate. >> reporter: it was supposed to be a night of fun, letting your hair down, saturday night had become early sunday morning, the music loud and funky. this video posted on the internet from inside club pulse around 1:00 a.m. last call, last dance, latin theme night was wrapping up. a crowd of about 300 packed into orlando's popular gay nightclub. approximately 2:00 a.m., everything changed, the gunman holding an assault rifle encountered an offduty police officer and exchanged fire with him. entered the club, shooting as hi moved. >> oh, my god, people are it going shot, dude. >> the music stopped, but the gun fire continued without cease. carlos ro carlos soez sar owe rosario

was -- >> 20 to 30 rounds went off. the first two rounds, everybody didn't really move because they thought it was part of the music, because the music was so loud. and when it kept on going, i think everybody's instinct went to this is not music, this is gunshots. >> oh, my god, they're all shooting back and forth. >> patron joshua mcgill described what he saw and heard. >> it was like boom, boom, boom. >> were people screaming? >> people laying on the ground, taking cover. jumping the fence. i think the pension actually broke with people pushing on it to get out. >> there was just too many shots, bang, bang, bang, that's when you know chaos, it was just turmoil. >> patrons trapped inside began

calling 911. four us still hiding, lights are off in club. cops are here, but haven't got us yet. thank you, i jumped out. there's people still hiding inside the closet, that the shooters don't know they're in there. the club managers managed to post this notice on their facebook page, everyone get out of pulse and keep running. if only they could. >> my son was in the nightclub what his boyfriend and other friends and i know that his boyfriend has been shot multiple times and is in the emergency room. >> reporter: the gunman armed with his rifle and a hand gun, was relentless. spraying a crowd jammed into what was ultimately only a small dance floor with nowhere to go. >> describe the chaos you saw. >> the guy started shooting, at least 30, 40 shots. >> reporter: outside in the parking lot, some of the gunshot

wounded were scooped up by police officers and pick-up trucks and rushed to emergency rooms. the s.w.a.t. team entered the club. outside, some people recorded the ensuing gun battle on their smart phones. >> let's get out of here. >> oh, my god, dude. >> authorities made the decision to end the hostage standoff. that went going in after the gunman. officers knocked through a large window in the club allowing officers to go in and rescue survivors. when the shooting stopped, the gunman lay dead. it was too much to take in. the numbers of dead and injured could only be estimated at first. orlando chief of police john mina. >> there are multiple people dead inside, i don't want to

give a number right now, but multiple people are dead inside, obviously our condolences go out to their friends and family. >> the survivors took stock of their luck but most of all. >> reporter: so now an orlando dance club joined the roll call, virginia tech, new town, connecticut, san bernardino, charleston, a movie theater in colorado. and then, just after 10:00 a.m., local and federal officials stepped up to the cameras with a sickening update. orlando mayor buddy dyer. >> since last update we have gotten better access to the building, we have cleared the building. and it is with great sadness that i share we have not 20, but 50 casualties. in addition to the shooter, there are another 53 that are hospitalized.

>> reporter: with that, the tragedy had achieved a milestone nobody wanted. some of the newest newest victims were the friends and families at the hospitals outside the crime scene, desperately waiting for any information about what had happened to their loved one. >> it's just unspeakable. you just don't expect your child to be involved with something like this. >> reporter: and by mid morning, the shooter had a name. omar mateen. he's said to be a 29-year-old divorced father working as a security guard, a u.s. born citizen of afghan parents. >> we contacted mateen's father in florida a couple of hours ago, who had quite a lot to say, first of all he wanted everyone to know that the family is

shocked by this, they apologize and say this is terrible. >> the father suggested a motive for the son doing what he did, storming a popular club on saturday night. hatred of gays. >> he the father, mateen the son and mateen's young son were in miami and according to the father saw men kissing, touching each other, this outraged mateen, he said to his father, they're doing this in front of me and my son. his father thinks this is what touched this off. >> reporter: but nbc's pete williams said sources in the community told him that mateen may have other reasons too. mateen is reported to have called 911 in the early morning hours to declare his allegiance to isis. later in the afternoon, the fbi told reporters that mateen was on the agency's radar as far back as 2013. >> the fbi became aware of mateen in 2013, w4ehen he made

inflammatory comments to co-workers. the fbi thoroughly investigated the matter, including interviews of witnesses, physical surveillance and reference checks. during the course of the investigation, mateen was interviewed twice, we were unable to verify the substance of his comments and the investigation was closed. >> reporter: a hand gun was recovered along with an ar style rival. mateen was said to have had proper permits for weapons. rick scott addressed the media. he was clearly shaken. >> right now our hearts and prayers go out to everybody that's been impacted by this. i can't imagine a family member that is still waiting to find out what happened to their loved one. it has to be heart wrenching. >> many of those spent hours at local hospitals. >> as has been mentioned, this will take some time and we ask for your patience. but we will reunite the family

and the victims just as quickly as we can. >> president obama was updated throughout the day. >> today as americans, we grieve the brutal murder, a horrific massacre of dozen s of innocent people. we pray for their families who are grasping for answers with broken hearts. >> reporter: once again he stood before the microphone in the after math of a mass shooting. >> an attack on any american regardless of race, religion, or sexual or generalatiientation i on all of us. no act of hate or terror will ever change who we are or the values that make us americans. >> an act of terrorism and hate, said the president. and shortly afterwards, an isis

affiliated media unit issued in statement. to the attack that targeted a night club for homosexuals in orlando, florida and left more than 100 dead and wounded was carried out by an islamic state fighter. so far no evidence as surfaced showing a connection between mateen and isis. those in the local lgbt community seemed too much in shock to believe they could have been the target in the latest isis campaign. >> i'm sad, i can't be angry right now. because we don't know itnoknow was an attack on the lgbt community or just an attack on a nightclub. right now, my main thing and the center's main thing is that we have got to remain strong and vigilant for our community, be there for them and help them get through this. >> reactions to the attack flooded social media, not just

the the area, but also from across the country and around the world. former congresswoman gabby giffords herself a victim of mass shooting posted a message on her website. this is a sad day for this country we all love. we want to say that this tragedy is unthinkable, but it is not, once again a mass shooting has torn a community apart. candidates for the presidency also weighed in with sorrow and condolences, bernie sanders said this, we are all saddened by the horrific shooting in orlando. hillary clinton went further, we need to keep guns that were used last night out of the hands of terrorists or other violent criminals. while trump criticized the obama administration in what he called islamic terrorism. what happened in orlando is just the beginning, our leadership is just the beginning, i called in

and asked for the bang, must be tough. foreign dignitaries also offered support, from italy, england's royal family, even the vatican. but it fell to those close to home to comfort grieving families, to deliver the news of life and death. and to find answers. florida governor rick scott. >> there's going to be plenty of time to deal with how our society comes together. i tell you the orlando year, the orange county, the state of florida, we're very resilient. we will come together. and do everything we can to help everybody that's been impacted but also bring us back together again. >> it was just another night out in one of the country's capitals of entertainment. they came to the pulse, the heart of life and found its opposite. >> what we know about the shooter and his motive for mass mu

no one ever knows what's in the mind of a mass killer, but interviews with his family and a phone call he made just before the massacre have given us insight into what might have motivated omar mateen. here's cynthia mcfadden with more. >> reporter: amar'ecy de omarcy ittie mateen lived about 25 miles from the pulse nightclub in orlando where he carried out the massacre. since 2007, mateen worked for the international security contractor g4s. according to public records he was a lbsed security guard and had a permit to carry a concealed weapon. on his myspace page, mateen is

seen taking selfies dressed in his new york police department shirt. early this morning tracey connor spoke exclusively to ma deep's father. how did he describe his son? >> he said he was his number one son, he was a great son, he was a son any father would love to have. >> his father said that omar might have reached a tipping point a few weeks ago in miami. when he was with his 3-year-old son, and saw two men kissing. >> this made him really angry and he said look at this. i can't believe they're doing this in front of my son. >> the father and son were in the men's room and there were two men who were showing affection to each other there. and the shooter became upset

again and you know mentioned it and said he was angry. >> reporter: the shooter's father said his son who got an associate's degree in criminal justice from indian river community college was not an islamic radical. >> well at the time that i spoke to him, the police had just come out and said that they were exploring the possibility that there may have been a link to radical islam. he was upset at the thought of it and he said, no, no, no. religion had nothing to do with this. >> reporter: but the growing evidence suggests mateen's father might not have known his son as well as he claims. one of his high school classmates tells nbc news, mateen was suspended in school after 9/11 for making remarks supporting the terrorists. and the fbi now running the investigation into the mass shooting confirmed at a press conference this afternoon mateen had been on their radar twice, but they had cleared him. shortly before he started his shooting rampage, mateen called 911.

nbc's pete williams. >> investigators say in that cal.l he expressed his support for abu bakr al baghdadi, and and also mentioned the 2013 boston marathon bombings and the two brothers who carried out those attacks in boston with dzhokhar and tsarnaev. >> why call 911? >> the islamic base has advised their support base if you're going to demonstrate support -- crusader media can't confuse that as a ran come act of violence. >> in the beginning he was a normal being that cared about family, loved to joke and have fun but a few months after they were married i saw his instability. >> she watched him turn from a regular guy who wanted to be a police officer into a man who became increasingly unstable. >> and i saw that he was bipolar and he would get mad out of nowhere. that's when i started worrying

about my safety and after a few months he started abusing me physically, very often. >> she says he used steroids and believes he visited gun ranges. she said he also tried to keep her away from their family until they sensed something wrong and came to visit her. >> my family literally rescued me. the night they were there they had to pull me out of his arms and by emergency flight i left my belongings. it took a year and a half to finalize the divorce. >> as for mateen's father, investigators are continuing to learn more. as of this evening he insists he is in shock, like everyone else. what did he want people to know? >> the fare, when i spoke to him, it was almost like he was pleading. he said "i want you to get this message out. we apologize. we apologize for what my son did. we are so sorry for all of these families.

at one point he described the families of the victims as his family. these are my family, he said. i'm an american and these are my family." >> and joining me now here is florida senator bill nelson. sorry to see you under these circumstances. >> thanks. >> i know you've been in touch, talked with investigators and anything to indicate this is more thanisis inspired that, there may have been a direct connection between mateen and isis? >> there is some evidence. the fbi, as you have already reported, had on the radar in 13 and 14, but no prosecutable evidence. so they closed the case. there is at the end of the day, i think we're going to see he's isis inspired, but i think we're also going to see this as a hate crime. that he was motivated by being anti-gay and whatever it is,

it's terrorism. and that's what the terrorist tries to do, to make people fear and that's what we have to overcome. >> i said it, you probably said it, millions probably said, oh, no, not again. what do we do about this? what do we really do to stop people from walking into a night club and opening fire. >> two nights ago we had a singer killed on the stage. >> reporter: christina remmie. >> yes. you remember sandy hook, my goodness, 26 people. well, this is bad enough, but americans cannot succumb to fear. if we'll dig down deep and face this, these animals will ultimately do themselves in. >> we don't submit to fear, but do we at some point admit to a sense of helplessness that mass shootings are going to be like

hurricanes, they just happen? >> no, we cannot have a helpless feeling. that's where it's so important, if you see something, say something. we have a great intelligence apparatus and if we can penetrate that network, if they make any kind of statement, then we can get them. but the fact is, that if it's a lone wolf, it's hard to be 100%. >> before i let you go, there was some brave police work last night and some folks doing some pretty grim work right now. how are they doing? you've been down there. >> they're doing great. all of them, they're right in the trenches, they're doing their job, they know this is for america. >> senator bill nelson, nice to see you.

>> they were like anybody, like you or me, a daughter, a son, a sister, a brother. out at night for fun, to live. >> what was it like to hear the screams of people who were still inside? >> it was horrifying. >> the lucky ones got out. >> when i doze off a little, i hear it all in my head again, i hear it in my head, i see it happening again, i'm like oh, my gosh. >> reporter: in the early morning hours, police investigated, relatives waited, desperate for news. wait any loved one any parent can understand, but dreads ever

enduring. christine flanagan was one of them. >> i don't know where my son is, no one can tell me where my son is. if he's been shot, if he's dead, no one knows. he's not answering the phone. but he was sitting right next to his boyfriend, and his boyfriend definitely was shot with multiple gunshots. >> he was shot? >> we don't know. >> reporter: another mother, lena justice, was outside the nightclub trying to find her 30-year-old son, eddie. he texted her from the club bathroom. >> what did he tell you? >> that the shooter had them in the the women's bathroom hostage, and that he was going to die. >> reporter: lena told the media that was the last conversation. >> i said was everybody all right, he said no, people are hurt. he said he has us and he's going to kill us. >> reporter: communication was so difficult, families went on social media for any information. survivors, those who escaped uninjured, understood intimately

how lucky they were. system, just because they happened to have been out of the shooter's direct path, like joshua mcgill, for example, who ran out of a back exit. >> it was like boom, boom, kboom, he was like pointing and shooting at whoever he wanted to. >> reporter: johnny l. gonzalez also escaped for his life. >> a lot of people thought that it was part of the sound effects from the music and stuff like that, but in realty, it was when i dropped to the floor and i saw people crying, people covered in blood, i smelled the scent of the actual bullets, i was like this is real, this is real, it's happening right now, we need to get out as soon as we can. >> reporter: politicians had trouble holding back emotion. florida governor rick scott. >> just the impact it's going to have on their families. i can't -- i mean, i've got kids, and grandkids, you can't imagine. >> reporter: mayor buddy dyer couldn't believe what happened in his city. >> today we're dealing with something that we never imagined

and is unimaginable. >> reporter: so wurns once again shock unsettles the country. that overnight in a place people go to celebrate, the margin between life and death was so very slim, that for many of the injured tonight, it still is. there was an orlando police officer there to help stop the shooting, this is his badly damaged kevlar helmet, because of this, he lived, is okay. 50 people, maybe more, were not as lucky. not at all. >> disbelief, panic and a frightening realtiy and a fight for survivor. christopher hanson and carlos rosario are among those who made it out alive. they shared their stories of survival with our harry smith. >> reporter: it had been a great night at the club, when all hell broke loose. christopher hansen is on your left, carlos rosario on your right. what was your first indication that something was wrong?

>> two shots went off and we thought it was part of the music, and that's when the rain of shots went off. and that's when everybody just -- it was like a mass of people trying to fit out of one tiny exit, and everybody was trying to get out as fast as they could. >> oh, my god, people are getting shot, dude. >> when i'm hearing, pow, pow, pow, pow, i'm like oh, no, not today. i was just down, and i was crawling and i was military -- i don't know. i wasn't in vietnam, but i felt like i was in war, like i don't know. it took me somewhere, and i crawled out and i felt cement, which i knew i was on the back patio. and that's when i got up and running, zigzagging, dodging these bullets. i just kept crawling. >> did you see people hit as you were crawling out? >> oh, yeah, yeah, yeah. >> they were like falling like flies. the two people that we saw, that got hit, he was actually behind

me. and there was a gunshot wound and he grabbed onto me, like he felt the pain or something, i got scared and i felt like somebody was trying to grab me. and i turned and and i saw him and then he turned around and he was bleeding on his leg. and i realized that could have been me, he was right behind me. >> who did you help? >> there was a gentleman named junior, he was 24 years old, he got shot on the right buttocks on top, almost on his back. that's when he took off his bandanna and held it in the hole. we held pressure for it. i got very emotional because i lifted it up and i saw it. i really wanted him to get through it. so i just closed it back and i didn't say anything. and it's just so much more serious than it is. and then the other girl, her hand, it was just horrible, it's just like these people will forever be traumatized and also see their scars from something they never would have thought would have ever happened

to them. i think the one scary thing that made it all set in is when we walked away from the area that the police officers cleared everything off. there was a section for the injured people. when he walked there, they were just in rows and -- >> and not even tagged yet or on stretchers. >> it was just like -- nfs just like nothing you ever want to see in your life. those are people, those are kids, those are somebody's father, son, mother. and just being there, and you can't do anything about it. it just puts everything in to into perspective. >> joining me now is patty sheehan, orlando's first openly gay commissioner. thank you for being here this evening with us. i know this is particularly personal. you know the owner of the nightclub. >> yes. >> this is your district. >> i have been in this nightclub, there but for the grace of god go i. i could have been out. this is a horrible tragedy, this is basically one of our main streets in orlando, this is just

blocks from city hall. a lot of small businesses have been impacted of course and this is a horrible tragedy. and the fact that they picked latin night. this is a community where everybody gets along and everybody embraces one another. i think the terrorists were trying to strike at the heart of that, but they're not going to, because they are a loving community in orlando. we are good people, and this is not going to take that away. you look down the street, there are these business owners and they are bringing food and water and all this to people. it's an incredible outpouring of love and support. >> hay heart went out, watching families earlier today, trying to find out what the status of their loves ones were, alive or dead. you've heard some stories. talk about thatening wish. >> i saw some of them on the street this morning, it was just horrible. and we're trying to do what we can. but when you lose someone like this, there's no words of comfort that are enough. the victim's service center is reaching out to them and they're getting assistance.

but you know i think there's just this sense of tremendous sorrow. i think that comes followed by anger as people run through the process of grief. we're going to have to support these families, people don't realize about orlando, we have a very caring community. victims service centers, gay, lesbian, bisexual, transgendered community center is doing grief counseling and has been doing it all day long. we have a gofundme page to help the victims, that's gonethrough the gay bisexual community center. these terrorists had to strike at the heart of who we are with hatred. and here's the thing, orlando is going to come back, they're going to come back with love. supporting people. and this is not going to destroy the fabric of this community. >> reporter: maybe it's our nature to want to classify everything right away. terrorism, international terrorism, hate crime. what is this? was this an attack on the gay community or was this an attack on america? >> i think both. it's unfortunately, because i see a lot of people out here today that i never see supporting the gay community yet

they're here today. and that's frustrating because gay americans are americans, and we bleed just like everyone else. my community bled on the sidewalk out here and were shot, and killed, and you know, we count. we matter as a community. we are human beings. we are people, and we are americans. and i'm distressed and so sad by this. i wear two hats as a city commissioner, i also am a member of this community and i'm so sad by the loss, but i also have to remember the people, the outpouring of love and support and everything that's happened in community that will continue to happen and the fact that they have not destroyed us, but we have got to have, i think a discussion about this violence and how someone can get so dysfunctional in this society that they think it's acceptable to take a firearm and take out as many people as they can. what even -- you and i can't even begin. >> reporter: that's what we're

all pondering. >> you and i can't even begin to put, understand that level. but we have got to start asking that question. these armed people who go and want to take out as many people as possible. we have got to ask that question. >> commissioner sheehan, sorry to meet you under these circumstances but thank you for your time tonight, we appreciate it. your time tonight. >> more on this particular pain of this tragedy in the lgbt tragedy and what this the history of mass shootings oh, look... ...another anti-wrinkle cream in no hurry to make anything happen. neutrogena® rapid wrinkle repair works... ...in one week. with the... fastest retinol formula available. it's clinically proven to work on fine lines and... ...even deep wrinkles. "one week? that definitely works!" rapid wrinkle repair. and for dark spots, rapid tone repair. neutrogena®. "see what's possible."

this is pride month a yearly >> more on this particular pain of this tragedy in the lgbt tragedy and what this the history of mass shootings reveals about us as a nation. this is pride month a yearly celebration that arose decades ago in response to today's violence, making today's shootsing all the more tragic. >> this is an act of terror, this is an act of terror against lgbt people. >> reporter: rachel chin has been fighting for lgbt equality for decades. what was your thought when you heard the news? >> a moment of i hope it's not true, or i hope it's not targeting us on purpose.

you don't want to believe that people hate you that much. >> reporter: for all the unknowns swirling around this terrible day in orlando, this much we do know, the killer had targeted one group of people. >> whether this is political disagreement or a crazy person, it almost doesn't matter. because attacking lgbt people, attacking a gay night club, speaks for itself. >> reporter: the awful news from orlando has stunned everyone in the lgbt community. we spoke with people gathered at the stone wall in, in new york the birthplace of the gay rights movement in america. >> i could have been there, i could have been at the wrong place at the wrong time and i could have been targeted just as these people were as a result of my identity and it's heartbreaking. >> seeing someone so sick to do something like this to our community, and innocent lives are lost because of this

tragedy. and we should all be able to be who we are and i can't believe that something like this would happen to our own community. >> beverly tillary is the director of the new york city anti-violence movement. >> to see people attacked at this place, it's more of a tragedy, because that's probably what many people were seeking was safety and community and what they got was completely the opposite. >> reporter: it's supposed to be a voice of joy and celebration, right? >> that's right. june is the month that we celebrate and here we are, in 2016, people still do not feel completely safe, even in their own nightclubs in their own community. >> reporter: with news of the massacre, police departments across the country beefed up security at gay pride events where suddenly it was hard to think or talk about anything else.

washington, d.c., detroit, des moines, philadelphia, boston. it was just a year ago that the white house was lit in rainbow colors to celebrate the supreme court's decision on gay marriage. today, president obama said the attack was especially heartbreaking, because the people killed had come to celebrate life. >> the place where they were attacked was more than a nightclub, it was a place of solidarity and empowerment where people have come together to raise awareness, to speak their minds, and to advocate for their civil rights. >> reporter: an attack, the president said, on every american. >> this action does not speak for islam, and it does not speak for american muslims. and lamda legal already received notice of condolence, outrage from muslim leaders asking how they can express their solidarity, how they can lead with us. >> reporter: today, all kinds of people, gay, straight, are

gathering in places like the castro district in san francisco. the stone wall in new york. >> the political success and the a advances that lgbt people. so many americans have embraced our pride and love of ourselves. >> reporter: you don't see this as an undoing of that? >> not at all. not at all. i think this will bring people out with renewed commitment that we are not done. >> i think every tragedy that continues to happen and it continues to escalate, i think they serve to galvanize us and remind us why it is we are here, these rights and privileges that we take for granted on a daily basis, the right to stand out here in the daylight and the right to even live and survive are at risk. >> today with this deadliest shooting in u.s. history, orlando joins a sad list, the very names evoke the horror of

mass murder, columbine, new town, awe rao rah, san bernardino. what does this history reveal about the killers, what does it reveal about us? here's "dateline's" josh mankowicz. >> reporter: the news always hits you in the gut. >> then i've just been trying all morning so i can't find them. >> i'm in shock, i feel like i'm almost like numb. >> what was it like to get that news this morning. >> shocking, very shocking. >> reporter: shocking? of course, but now it shouldn't come as a surprise. mass shootings are a familiar and undeniable part of american life. the settings are defined by how ordinary they are. places where people go every day to simply live their lives -- college campuses, restaurants, elementary schools, military installations, and last evening, a nightclub. >> i just feel terrible. i don't know where my son is. >> reporter: where else in the western world do these shootings happen with such numbing

regularity. the answer is nowhere. they are so commonplace, we even have a way to define them, a mass shooting means four or more people have died. they tear at the fabric of our society. where can we feel safe, at the mall? in school? our churches? what kind of nation are we? it's a question with a history. a long history. >> there's just been a gunshot. on the main plaza. >> reporter: this year will mark the 50th anniversary of a shooting at the university of texas that claimed 16 lives. [ siren ] schools especially have been targets. before today, the shooting at virginia tech in 2007 held the sad distinction of being the worst ever in terms of casualties. the shooter in that incident killed 32 people. then took his own life.

sandy hook elementary school in newtown, connecticut is seared into our memories. what could be more innocent and beautiful than young school children. 6 and 7 years old, 20 of them, and six adults were gunned down by adam lanza at 20, not much more than a child himself. columbine, ft. hood, the screening of a new "batman" film. the emanuel church in south carolina. >> we're tired, we're fed up with this, we got enough. >> >> reporter: places where is we think we're state of, place where is we should be safe. these events come and they go, but they never stop. last december, the bbc reported a shooting in san bernardino, california as -- >> just another day in the united states of america. >> reporter: the orlando shooter called 911 and swore allegiance to the head of isis. but more often than not, mass shootings have not been

about terrorism. what drives the killer, intolerance? racism? maybe. you can look into their eyes and see isolated troubled minds, with motives we might never truly know or understand. >> oh, my god, dude. >> reporter: maybe this was a case of extremist terrorism, but what of our long history? that speaks to something else. something terribly wrong within our society. where a broken soul and a loaded gun have led to so many tragedies. today is surely the time to think about the victims. >> today as americans, we grieve the brutal murder, horrific massacre of dozens of innocent people. >> reporter: president owe what obama sad today that we need to do more. >> although it's still early in the investigation, we know enough to say that this was an act of terror and an act of

hate. and as americans we are united grief, in outrage and in resolve to defend our people. >> reporter: this will be a year of decisions. and there will be talk about how to prevent terrorism from hitting us at home. that debate will be heated. but who can speak to our long and sad history of violence? and the question that is surely on the minds of all americans tonight. when will the killing end? >> joining me now from new york is tom brokaw. tom, we have seen this movie far too many times, even the conversations that follow are the same. how do we get off this hamster wheel? >> lester, i've been thinking about that a lot today, and obviously and appropriately this is going to be part of the presidential debate. it's already started. there's a lot of vitriol, a lot

of bombasts. the victims in this case, the people who were killed, their families and the american people for that matter deserve better than this. mateen claimed it was acting on behalf of the head of isis, it looks like he was just freelancing, also what was the role of his revulsion as described by his father of gay and lesbian behavior. we don't know what he was exposed to on social media. we don't know why, if the fbi interviewed him twice he was able to get his hands on an ar-15. that's a military assault weapon. it's designed to do one thing, and that's to kill people. was he so enraged by what he was reading and seeing her that he had to do this irrational act? we don't know that, but we need to have a rational debate on how we're going to dealing with this war, the likes of which we have never been involved in before. it's run by a shadow which group

in the middle east, very elusive, very clever, and also has their eyes set on us. all the mass shootings, in fact the minority of the mass shootings have been triggered by islamic rage. there have been so many other mass shootings in america as well, between san bernardino and what happened here today tragically. >> tom brokaw, tom, thank you. when we come back, the very latest on the investigation. and a look at the day's most unforgettable images. e day's mo unforgettable images.

as we have heard, the gunman, omar mateen made a 911 call pledge of allegiance to

isis before he started shooting. what does this tell us about homegrown terrorism. here's "dateline's" andrea canning. >> reporter: in the hours after the mass shooting, as always, people have questions. why now? why a gay nightclub? nbc terrorist expert evan coleman coincided with the recent call for violence. >> it has been telling people not only in the last few months, the last few days, but in the last few days, the smallest action you can carry out on your own inside the united states is better than anything you can do here. >> reporter: you talk about these soft targets and you believe that was the case in orlando. >> this was a target that this individual knew that he could get to, he would kill and hurt a lot of people before anybody would be able to stop it and no one would see it coming. >> reporter: holman believes it was a target because isis is violently anti-gay. >> isis would like nothing more than to send a chill through the heart of people going out an a saturday night.

isis' have broadcast pictures of themselves throwing homosexuals off of buildings inside syria and iraq. it fits in their agenda, something they can applaud adwr aggressi aggressively. >> reporter: how are they deciding i'm going to carry out the actions of isis? >> what's amazing is that isis really has quite an effective propaganda machine online. in every mechanism you can think of. twitter, kick, every social media platform that has come to be used in the west is used on the other side as well. >> reporter: pullman says it was clear the jor lan dough shooter was paying attention to other homegrown terrorists. the shoot ear parentally mentioned the boston bombers in his 911 call. what does that tell you? >> unfortunately what it tells us is that there are now individuals here that are becoming icons for american terrorists. there are people that are now idols for to us follow. >> reporter: one of the people involved in the boston bombings, the san bernardino couple were all on the fbi's radar at one time or another, and yet these

attacks still happened. >> this is the motive of local law enforcement, who has simply been radicalized who is innocuous, versus someone who say potential viable threat. the fbi does not have the resources nor will they have ever the resources to be able to constantly track every single person who is suspected of being radicalized. >> are we almost succeeding war with the larger terrorists groups as far as thwarting plots than we are at home from the mass shootings? >> it's fair to say that the u.s. government and the u.s. in general has done a much wetter job in terms of stopping terrorist networks in isis, than the broadline problem of propaganda and recruitment. there's good news and there's bad news. there's not hundreds of thousands like, this there'ses

dos of people like this. >> reporter: joining me is justice correspondent pete williams and joining me in new york is tom brokaw. tell us about this phone call to 911 omar mateen made. >> at some point while he was inside the nightclub he called the police, got on the phone with them and said that he was pledging support to abu bakr al p baghda baghdadi, the we of isis. brothers, dzhokhar and tamerlin tsarnaev who carried out the attack. but this call expressing support for isis are wondering whether this was inspired or was he in touch with foreign terrorists

and so far the answer to that latter question as to whether he was in touch with specific terrorists overseas is peers to be no. >> and tom, is this going to require a more international response? we're looking at this almost as domestic terrorism, inspired overseas. will it require a different response? >> it will, and i think it's going to take the breast brains and the best efforts of all of america's allies, and i'm keenly disappointed and that's putting it lightly that we don't have more action and support from arab allies like this, like a saudi arabia speaking out or qatar or the united arab emirates. we need everyone involved. those nations are as much at risk as we are, they're living in a kind of state of paranoia and terror constantly that will come home to them, too, if isis takes over as they hope will at

some point. i've been doing this for 50 years, as you know, lester, i never thought this is where we would be at this stage in american life. as a grandfather, as a father, as a journalist, i thought we'll be able to solve the issues that come before us. this one will require a different kind of effort. >> this is one of the people that was on the fbi's radar and yet this happened. does this illustrate how difficult this is? >> it sure does. it's always hard to know when someone is popping off about violence, whether they're somebody you can continue to surveil. they say they looked at him twice, case closed and there was nothing in the past that looked like he was going to go radical like this. but the picture of himself now is somebody who was a very violent man, lester. >> pete, thank you. americans today spending another day trying to fathom a mass shooting in our midst. huddled on a late spring sunday around screens filled with

horror and heartache, we end tonight with searing images from orlab dough. >> good morning. breaking overnight, mass casualty shooting, a horrific scene outside a popular nogay nightclub in orlando when a gunman -- >> i don't know where my son is, no one can tell me where my son is, if he's been shot, if he's dead, no one knows. >> we are mourning. we are sad. we are heartbroken. >> we need to rally around the

family and the friends of those people who were killed today. ♪ >> and all the ugliness that happens in the world cannot outshine what's in our hearts and that is to love. you will not break us. we are better people than this. >> say a prayer for them. say a prayer for their families. that god gives them the strength to bear the unbearable. >> there will be continuing coverage of the massacre in

orlando tomorrow on "today" and i'll be with you then, and alsoing "nbc nightly news" tomorrow night. there's more on msnbc and on your late local news as well. we'll bring you tonight's originally scheduled edition of "dateline' on assignment sometime soon. i'm lester holt. from all of us here at nbc news, thank you for watching and good orlando nightclub massacre are slowly being leased by authorities this morning. it is the worst case of terror on american soil since september 11th. the deadliest mass shooting in our nation's history, took place early sunday. 29-year-old omar mateen armed with an ar-15 type assault rifle and handgun opened fire and took hostages. when it was over, 50 were killed and 53 injured. nbc news has learned from law enforcement sources