this is "nightline." >> tonight, newsroom attack. >> this was a targeted attack on the "capital gazette." >> a gunman opening fire at a newspaper office in maryland. >> this guy was holding what looked like a big shotgun. pointing the gun deeper into the office. >> at least five killed. >> victim's coming out. >> reporters becoming the story, describing the moment of terror, hiding under desks, listening to a massacre unfold. >> he was like, you need to get out! >> now the latest in the investigation. the suspect taken alive. his personal grudge against the paper uncovered. could that have motivated a suspected killer? >> "nightline" will be right back.

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surprise! i got a puppy. add an ipad to select packages for just $5 a month for 24 months. upgrade online now. good evening. thank you for joining us. we begin tonight with the attack on a maryland newspaper. a gunman with a grudge storming the newsroom, killing at least five. among them a father of three, a mother of four, a soon to be married young woman, a sports lover, a devoted husband. tonight we're hearing survivors describe the frantic assault that claimed the lives of these beloved journalists. here's abc's geo benitez.

>> victims coming out, victims coming out. >> police are confirming two down at this point, two down. >> reporter: the number of casualties quickly rising. >> four down. >> reporter: we now know the number to be five killed, all of them journalists, at least two more injured. >> heard a loud noise, incredibly loud bang. saw a guy holding a gun. the door of the "capital gazette" had been blown to pieces. >> several shots have been fired. possible shotgun, at least ten shots heard. >> reporter: tragedy hitting home for this local newspaper in annapolis, maryland, the "capital gazette." early this afternoon finding themselves at the center of a national story. an active shooter situation unfolding inside the newsroom. >> he entered the building with a shotgun. and he looked for his victims as he walked through the lower level. >> all units limit your transmissions. do we have any kind of intel on our shooter?

>> white male with a ponytail. >> reporter: in about 60 seconds, authorities responding, running inside, engaging the suspected shooter. minutes later the suspect, who police say used a shotgun to carry out his assault, surrounded by officers and taken into custody. >> the shooter is in custody and being interrogated at this time. >> reporter: the suspected shooter has been identified as 38-year-old jarrod ramos, who may have had a long-running feud with the paper. having sued the paper in 2012 after it reported that he pled guilty to criminal harassment. the newspaper won the case, reporting on what was already public record. >> mass shooters are what typically are called revenge collectors. in other words, their revenge builds up and it can be as simple as an editorial that might have been written. or a lawsuit that they have lost. the triggering mechanisms for violence tend to be, in these types of cases, tend to be built -- they build up over a

period of weeks or even months, and possibly years. >> reporter: heavily armed police working to get p safely. about 170 people evacuated, hands in the air, to a reunification center at a nearby mall. >> we're doing everything we can to get people out safe. and we're trying to minimize the casualties. >> reporter: the scene unfold behind me, and take a look, hours later the scene is still active. police using dogs to search for explosives or possible accomplices. authorities say they found a canister of smoke grenades. >> this is what we train for. a week ago we practiced an active shooter training thing. we did not expect something like this to happen in our community, but we were ready. i don't think we could have put any more resources, if you look behind you at what's been done here. >> reporter: afterwards eyewitnesses sharing harrowing stories about what happened inside that building. >> police came through knocking on our door, grabbing a door, and thin checking to make sure we are okay.

next thing you know he's like, you need to get out! we had to leave out the building with hands up behind the building beside us. >> reporter: describing the alleged gunman's movements. >> guy holding what looked like a big shotgun and moving across the entrance of the "capital gazette" office, pointing the gun deeper into the office like he was targeting people. >> reporter: newspaper reporter phil davis was inside the newsroom writing on twitter, gunman shot through the glass door to the office and opened fire on multiple employees, can't say much more, and don't want to declare anyone dead, but it's bad. in another tweet, there is nothing more terrifying than hearing multiple people get shot while you're under your desk, and then hear the gunman reload. amidst the chaos, the "capital gazette" steadfast in its missio keeping the website updated with warne.es interviewings a an employee saying, i'm a police reporter, i write about this stuff, but as much as i'm going to try to articulate how

traumatizing it is to be hiding under your desk, you don't know until you're there and you feel helpless. >> the sort of general level of animosity against the media, and secondarily maybe law enforcement in recent years, is very troubling to me. because people who are on the edge of doing something will use the discontent of others to sort of motivate and sort of rationalize their act of attack. >> reporter: the president tweeting with the familiar, my thoughts and prayers are with the victims and their families, thank you to all of the first responders who are currently on the scene. officials say the suspected shooter was apprehended with no wallet and no identification. what's that process like to identify someone who doesn't have an i.d., and they just do something like this? >> when you have no i.d., no wallet initially, that is a hurdle police have to get over. but with all the different means that they have of using

photographs, surveillance videos, talking to witnesses, turns out this suspect may have had some kind of ongoing feud with the paper. it gets done. >> so the early reports right now are that perhaps this was very targeted to this specific paper. >> exactly. and again, the police described this as a classic hometown paper. one that they do business with all the time. to get information out to the community. just a tragic loss for everyone involved. >> reporter: tonight authorities are searching his maryland residence for further information. >> because you have a shooter that's alive, that means you have to prosecute him. did you have to prosecute him, you really have to know the tick-tock of what led him to this shooting. the weapon, other potential people involved, and what took him up to the door of the "capital gazette" today. >> reporter: this attack marks the 154th mass shooting this year. that is a shooting with at least four fatal or nonfatal injuries.

tonight, we learn the names of the victims. >> first victim's name is wendy winters. second victim is rebecca smith. third victim is robert hiason. fourth victim is jerrold fishman. third victim is john mcnamara. >> reporter: the baltimore son reporting rob hiason, father of three, had just celebrated an anniversary. jimmy butts with a series of defiant tweets about the heart of the humble newspaper. devastated and heart broken, numb. the reporters and editors put their all into finding the truth, that is our mission, will always be. and tomorrow there will be a print edition. for "nightline," i'm geo benitez in annapolis, maryland. >> geo will be live on "good morning america" tomorrow with the latest details in the shooting. to our peers at the "gazette," we're with you. we'll be right back.

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and... who's there? hey. a boy? you never told your dad and me about any... wait, what's going on now? move the flag. ♪ ♪ tonight we take you on a journey to bolivia, where species as elusive as it is exotic swims the zam river. pink dolphins are legendary but their numbers are dwindling. can the dedicated scientists we'll meet help save their species? here's abc's victor oquendo with another look. >> reporter: they're the world's most intelligent animals, second only to humans. dolphins are majestic and playful. but there's one rare subspecies that remains a mystery to scientists.

the pink dolphin of the amazon river is a living legend. at the end of 2017, we caught our first glimpse. right now they've got one dolphin. you can see it right there behind me. it's totally surrounded. the world wildlife fund is on a mission to tag 15 dolphins throughout brazil, colombia, and here in bolivia, to study their health and behavior. the group consists of local fishermen and scientists. scientists fear the pink river dolphin is vulnerable to extinction. due mostly to manmade threats like mining, hunting, and deforestation. waiting for them under tents is a makeshift o.r. >> they're bringing the dolphin out of the boat. very quick process. they move fast. >> reporter: pink dolphins can only be out of the water for just under 60 minutes. with the clock ticking,

veterinarian karla sanchez and her team hydrate the dolphin to lower its stress. >> checking the temperature. they will work in a sequence. they will start with checking the health status and then do some measurements on the dolphin. >> reporter: as they conduct a its tail, then take tissue and blood samples to test for mercury, toxic substances, and general health. sign fists don't know for sure how these freshwater dolphins get their pink color. hypotheses include diet, water quality, and sunlight exposure. but they do know they get pinker as they age. a pink dolphin, why aren't they more well known? >> i think we didn't communicate about these dolphins. they are very attractive. they are more cute, in my opinion, than the marine dolphins. >> reporter: and as quickly as it came out, the dolphin is returned to the water. pink dolphins are known as an

indicator species. highlighting the overall health of the amazon. if they're doing well, so is the river. but deforestation has been changing the water. >> all the deforestation is having an impact because the less trees that means there's more runoff. and more runoff means there's more sediment getting into the rivers. >> reporter: that sediment can prevent the dolphins from swimming freely, as it did in 2010 when these trapped dolphins had to be rescued. eight years later, deforestation is an ongoing concern. it's just after 4:00 a.m. we just got up, about to drive two hours into camp, then head right out into the amazon. with one more dolphin to tag, we embark on a nearly three-hour journey through punishing terrain. you have to be real careful on these roads. road -- it's more just mud and water. for those who get trapped that mud can seem like quicksand.

>> bolivian ingenuity at its finest. >> reporter: it's such a trek the team of local fishermen and scientists set up overnight camp here. 35 people total eating, resting, and working together during their mission to tag the dolphins. leading the tracking charge is paul van dam, a biologist and director of bon agua, a bolivian ngo. >> you want to know how far they travel, how far the males travel searching for females, searching for family, searching for food. >> reporter: and just minutes after boarding our canoes -- a downpour. >> we are now in the rain. a bit unlucky. but rain does not interfere in the capture of the dolphin. >> reporter: the ride out is bumpy. after an hour, the fishermen find a lookout point for the elusive dolphin.

>> we are now setting up our camp. so the fishermen are preparing the setups to put the nets to capture the dolphins. >> reporter: while some work frantically through the cold rain, others take refuge in the much warmer amazon river. when the rain finally settles, it's go time. the team starts by checking its vitals. right now they have to work as quickly as possible, they also want to make sure to keep it very calm. that's why i'm talking very slowly right now. with the examination complete, the tagging begins. each tag will ping data back to a satellite once a day.drill, c your toolbox, becomes vital to tracking these mammals. >> first thing they had to do was disinfect the whole area. then give it an anesthetic.

look, one guy right here, all he's doing is holding the snout shut. >> reporter: because the dorsal fin is made of collagen, the pain will be minimal. they're inserting it right now, a mixture of blubber and metal. and within moments, the tracker is attached. >> now there's a rush to get it right back into the water. and she's set free. for people in the united states, what do you hope they learn? >> it's important that you have to be aware that the conservation of this type of species is something global. i think we need support from the global community to conserve this l on how to protect this mysterious and beautiful animal.

for "nightline," i'm victor oquendo in baya vista, bolivia. and next, david bowie, now the star man of his own museum exhibit. our behind the scenes look. ♪ there's a starman waiting in the sky ♪ man: it takes a lot of work to run this business, but i really love it. i'm on the move all day long, and sometimes i don't eat the way i should. so i drink boost to get the nutrition i'm missing. boost high protein now has 33% more protein, along with 26 essential vitamins and minerals. and it has a guaranteed great taste. man: boost gives me everything i need boost high protein. be up for it. bowlet's do it. ? .

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last month, 3,000 david bowie look-alikes converged on the brooklyn museum in new york city for a massive dance party in honor of the late legend. tonight we take you inside the new exhibit inspired by his legacy. "nightline" welcomes ashen singh. >> we're at the brooklyn museum, home to "david bowie is" exhibit. we've got about 500 artifacts from the david bowie archives and the curators agreed to show us around. let's check it out. ♪ ♪

>> david bowie's probably the best visualizer of rock 'n' roll music. he created a character for each album. ♪ ♪ this is the starman suit he wore on bbc in 1972. ♪ there's a starman waiting in the sky ♪ ♪ he told us not to blow it t >> as an artist, as a gay man, he let me be the person i always wanted to be a huge inspiration. ♪ ♪ >> let's dance, baby. ♪ ♪ >> he was amazing. the whole culture, new york,

being who you are. >> good job, ashen. you can find the "david bowie is" exhibit at the brooklyn museum now until july 15th. thank you for watching "nightline." as always we're online on our "nightline" facebook page. thanks for the company, america. good night.