this is "nightline." >> tonight, how did those three suicide bombers pull off such an elaborate and synchronized attack? at one of the world's busiest airports? new images of the suspects behind that terror in the terminal designed to cause maximum harm. and the fourth of july warning tonight here at home. plus -- >> whoa! >> a crash course in sharks. under the cover of night, a whole new way of looking at the ocean's dangerous predators. the breakthrough technology shining a light on the dark shark world. and all's fair in love and selfies. the dad going viral. imitating his teenage daughter's

self-portraits. taking matters into his own hands to make it stop. but first the "nightline 5." >> hurry in for the jcpenney fourth of july sale, $4.99 arizona tees for the fa tlm reserve family. swim wear wear for him and her. get $10 off a $25 purchase with coupon. that's getting your penny's worth. tired of redosing antacids? try duo fusion. new two in one heartburn relief. the antacid goes to work in seconds and the acid reducer lasts up to 12 hours in one

good evening and thank you for joining us. i'm rebecca jarvis. the big question, how could

those three suicide bombers pull off such a complex attack at one of the world's busiest airports? new images of the men believed to be behind the carnage and the panic they caused. the somber warning tonight for the holiday weekend ahead here. abc's terry moran reports from inside ataturk airport in istanbul. >> reporter: tonight, new details emerging in the terror attack at the airport in istanbul that left 42 dead and 238 injured. for the first time we see the face of one of the suspected attackers. the man in the baseball cap wearing a winter jacket on a summer day. just before 10:00 p.m., officials say, he and two accomplices pulled up in a taxi to istanbul's ataturk airport. the attackers got out of a taxi at the front of the airport where the first layer of security is. they were spotted and scattered. one heading down that way opening fire, detonating his explosive. another making it into the

terminal there. you can see the busted windows. the third going downstairs where people were waiting for rides and detonating there. unleashing a combination of deadly fire inside the airport. >> that's when i saw him in the corner. i saw the bullets flying. >> reporter: terminal surveillance camera captured this image of the man believed to be one of the gunmen. some people cowering in terror. others running for cover. then an explosion. >> first we heard the ground fire. after we heard the screamings. everybody starts running. >> reporter: this airport security video appears to show the lower level of the international terminal as another one of the bombs goes off. >> people were shooting on one side. we all ran the other way. then the bombs went off. >> reporter: one of the attackers detonated right here. and this area is the arrivals hall where people were waiting for their loved ones. in the confusion, acts of bravery. this video shows the seconds before an extraordinary takedown. as families flee, a gunman rounds the corner chasing them.

but he's shot by a police officer and collapses. his gun sliding across the floor. the officer approaches but runs for cover as the terrorist writhes on the ground fumbling to detonate his suicide vest. the turkish police officer who took down one of the terrorists as you could see in that security camera video, tonight he is in the hospital, he was shot during the takedown. he says he didn't feel any of the bullets hit him. >> that was quick, decisive action. you're dealing with people that don't care if they live or die. >> reporter: some improvised to help the injured, using luggage carts as gurneys. >> a very bad ending. one guy had holes in his back from shots -- from glass. >> reporter: steven, freelance journalist working for abc news, describes the ensuing panic. passengers ran down corridors and he desperately tried to find his wife. >> i saw the sea of people flooding toward me. i was just pushing through them, trying to get through to her. i was praying to god that she didn't leave the area as long as

i could find her, at least i could take her to safety. >> reporter: outside the airport the terror wasn't over. a third attacker was waiting. detonating his suicide vest near a line of taxis as some people ran towards what they thought was safety. you can see the force of the blast. bodies on the ground. >> people's natural inclination is to go outside. you dead nate the bomb outside and what's on the outside of an airport? glass. with an explosive like that, that's going to inflict mass casualties. >> reporter: hundreds of injured rushed to the hospital. the attacks sending shock waves throughout the world. in canada, president obama vowing to strength.the fight against terrorists. >> they're going to be defeated in syria, they're going to be defeated in iraq, they're going to be on the run wherever they hide. >> reporter: no terrorist group has claimed responsibility for the attacks but the turkish prime minister and u.s. officials say it reeks of isis. >> despicable attack at istanbul's international airport yesterday certainly bear the

hallmarks of isil's depravity. >> reporter: cia director brennan warning, as he has before, the main goal of isis is to successfully attack in the united states. >> if anybody here believes that the u.s. homeland is hermetically sealed and that the daesh or isil would not consider that, i think i would guard against that. >> reporter: in america, heightened and visible security at airports. >> no more tears. >> reporter: passengers who left turkey before the attack, some learning in the air watching tv, were shaken arriving here. >> i couldn't believe it. we were just there a few hours ago. >> i'm shaking. but i'm relieved. thanking god that i was in the air and that he was watching over me and that i was fine. >> reporter: at jfk airport in new york this morning one terminal was evacuated after an unattended bag was found. if travelers are on edge, they have reason. there have been nearly 60 attacks at airports in the past

year. most recently the horrific attacks in belgium three months ago. where three terrorists set off twin blasts at the airport in brussels. the attacks killing 32 people and injuring hundreds. >> you look at what occurred in brussels at the airport, which is almost simultaneously across the board, and you look at this. it's much more methodical in the way they planned it. >> reporter: experts say the airport in turkey has tight security in the departures area of the international terminal. passengers having to go through security checkpoint before they enter the building with visible armed security officers. >> what i found interesting about the attack yesterday was the fact that it was in the arrival area, which is a little bit less secure and not as strict as the departure area, which makes me think they did recons sans and understood that, or had help from inside understanding vulnerable areas of the airport. >> reporter: security experts say the front of airports are soft targets for terrorists

designed with participatings' ease and comfort in mind, rather than safety. but they say there are ways to improve security. >> highly visible, armed officers in the front of the airport does alabama act as deterrent. >> reporter: reinforce the physical structure. >> put more steel, reinforced concrete in that front area of the airport. put things like mylar on the glass. >> reporter: use innovative technologies. and three, pass legislation or regulatory action. >> airports aren't going to do this because it costs a lot of money. unless they're told to do it, they're not going to do it no matter how much security sense it makes. >> reporter: now that summer travel season is under way, today the state department is recommending travelers use situational awareness. >> we're simply reminding americans as if they need reminding, be up to date on the current information to bring street smarts. >> reporter: in istanbul is airport is open but evidence of the horror remains. workers wiping off traces of

blood from the walls. vendors opening up shops by shattered glass. some of the other damage hidden by temporary walls. with isis calling for attacks during ramadan and an american holiday coming up, everyone agrees the attack in turkey won't be the last. for "nightline" i'm terry moran in istanbul. >> thanks to terry moran. much more on "gma" in the morning. next, going deep. for a new look at an ancient predator. and say cheese-y. why this fed-up dad is going on a selfie spree. and say cheese-y. why this fed-up dad is going on a selfie spree. and that was amazing. along with support, chantix (varenicline) is proven to help people quit smoking. it absolutely reduced my urge to smoke. some people had changes in behavior, thinking or mood, hostility, agitation, depressed mood and suicidal thoughts or actions while taking or after stopping chantix. some had seizures while taking chantix. if you have any of these,

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and now a new view of an often violent ocean predator. the shark. until now it was nearly impossible to get a clear picture of their nocturnal hunting patterns. tonight we're taking you deep into shark-infested waters to see these mysterious and mythical creatures like never before. jesse palmer is taking the plunge. >> now's kind of the moment where nerves, they're kind of picking up. >> reporter: it's dusk off the coast of the bahamas and we're headed out further into the deep. preparing for a dive in the shark-infested waters in complete darkness. >> it's getting harder to see down under. i'll be honest, i'm having second thoughts. >> you're going to see a lot of sharks. the lights don't really shoot out that far. so we're really only going to see them when they're right on top of us. >> reporter: for a chance to see one of the ocean's deadly

predators as few have ever seen them before, it's worth the risk. >> oh my god. >> reporter: scientists have tried for years to research and record the nocturnal hunting patterns of these sharks. >> unbelievable! >> reporter: their findings, previously limited to gainey night vision footage. now revolutionary advances in low-light cameras are allowing them to clearly see the sharks, even under cover of darkness, for the first time. >> you look through the view finder, it looks like the middle of the day. >> reporter: making it possible to closely study their nighttime hunting habits and capture jaw-dropping shots like this. >> whoa! >> reporter: a great white off the coast of south africa breaching in the moonlight for a discovery "shark week" special "air jaws, night stalker." >> i think these new cameras are going to allow us to see into the nighttime world of the great white shark like never before. >> reporter: before i can dive to see the secret world of

sharks i have to get my feet wet during the daytime to prepare. we're going to get up close and personal with sharks. i'm ready to go. i get a crash course in diving. >> what's up, man? >> reporter: meet with my guide, andy casa grande, renowned underwater cinematographer who studies shark behavior. >> i've been diving with sharks 15 years now all over the world. filming at night can be a challenge because you can't see them until they come into range of your lights. once they disappear from the lights it's basically anyone's guess where they went. the last thing you want is a shark to sneak up on you in the dark. it gets a little sketchy, i won't lie. >> the number one rule i live by is to not act like prey. if you act like prey, the sharks treat you like prey. >> how do you act like prey? i don't want to do that. >> frantically pan and i can swim away. sharks get a bad rap but for the most part they're polite predators, really chill. >> polite predators? >> yeah. they could kill us -- >> politely?

>> but it's pretty unlikely. worst-case scenario is we could die. best-case scenario is having a good time, learning about sharks. >> reporter: i'm hoping for the best-case scenario. the reef sharks are in full force. >> are you ready to do this, buddy? >> reporter: we jump in with nothing but our scuba gear and wet suits. no cables. >> it's pretty amazing down here! >> oh my god, did you see that? crazy. >> they're literally everywhere. >> that's way into my personal space. i got to be honest, i thought i was going to be completely freaked out here amidst all these sharks. there's something very calm. during a night dive it might be different. >> reporter: when it comes to hunting in dark seas sharks have a biological advantage. their heightened senses include powerful night vision. reflective cells behind the retina allow sharks to see ten times better than human in the dark. also crucial, their sensitivity to vibrations in the the water.

allowing them to feel what they can't see. for sharks to be able to hunt in essentially total darkness, their prey has to be hypervigilant, hyperagile. so whatever they're hunting almost have no chance. >> reporter: these abilities make tracing their nighttime hunting patterns particularly important for researchers. >> let's rtry this area. >> reporter: using sonar to track their movement as the sharks stalk seals. >> look at that. >> reporter: this adeptness is also what makes diving with them in pitch-black waters so daunting. when the scientists in south africa follow the great whites into the deep, they have a cage to protect them. >> coming in hot. whoa, chris, you okay? the shark tried to get in the came with you. >> reporter: once again, we're going in without one. >> they are more prone to being a bit more feisty and competitive at nighttime. you're a big dude, you're fine, you can just punch one. >> yeah, they're only 12 feet, it's fine. >> you'll see how good their vision and is their senses.

they can clue in on anything. even in total darkness. i think it's going to be pretty epic. >> reporter: it's go time. >> seemed like a good idea three weeks ago, three hours ago. i'm wondering, what am i doing right now? >> run, run, run! >> it's freezing. it's like you're in the abyss. you can't see anything. you can't hear anything. oh, boy. this one's a big one. it's a really, really big -- oh, geez. oh, my god. >> whoo-hoo! as you can see, or not see, you look at them in the darkness, a shark could be right in front of us. until it swims within our light range, we don't see it at all. >> it's coming right for me again. >> crazy. he's literally right beside you one second, then the next second, disappears completely into the darkness. i have zero idea where this

shark is. here it comes. oh, wow. this thing's really getting up close and personal. >> pretty much finding different angles so they can surprise their prey. >> such an advantage, their ability to see, to smell. the electromagnetic feel fields. all the different tools is why this is the perfect killer. we're still alive, best news. i think i have all my fingers. second-best news. it was just so eerie down there. you have some of the world's greatest predators literally circling you without any concept of where they are. >> that's sort of their realm, their world. sharks love to use that element of ambush. >> and we sdifd. that was awesome, something i'm never going to forget. an epic experience with some of nature's most powerful hunters lurking in the departments just out of sight. for "nightline," i'm jesse palmer in the bahamas.

>> you can see "shark week" all week on discovery. up next, the dad with the unconventional approach to try to change his teenage daughter's behavior. i'm billy, and i quit smoking with chantix. i had a lot of doubts going in. i was a smoker. hands down, it was, that's who i was. after one week of chantix, i knew i could quit. along with support, chantix (varenicline) is proven to help people quit smoking. chantix definitely helped reduce my urge to smoke. some people had changes in behavior, thinking or mood, hostility, agitation, depressed mood and suicidal thoughts or actions while taking or after stopping chantix. some had seizures while taking chantix. if you have any of these, stop chantix and call your doctor right away. tell your doctor about any history of mental health problems, which could get worse or of seizures. don't take chantix if you've had a serious allergic or skin reaction to it. if you have these, stop chantix and call your doctor right away as some can be life-threatening. tell your doctor if you have heart or blood vessel problems, or develop new or worse symptoms. get medical help right away

if you have symptoms of a heart attack or stroke. decrease alcohol use while taking chantix. use caution when driving or operating machinery. most common side-affect is nausea. life as a non-smoker is a whole lot of fun. ask your doctor if chantix is right for you. try cool mint zantac. hey, need fast heartburn relief? it releases a cooling sensation in your mouth and throat. zantac works in as little as 30 minutes. nexium can take 24 hours. try cool mint zantac. no pill relieves heartburn faster.

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the dad who's had it with his teenage daughter striking a pose. the ingenious and now viral way he came up with to make her stop the selfies. you know the old saying, if you can't beat 'em, join 'em. well, that's what this spokane, washington, dad thought would be worth a try. when christopher burr martin thought his 19-year-old daughter was posting too many selfies he knew she wouldn't listen to traditional parental nagging. instead martin dubbed selfie dad began imitating her. >> i was like, tone it down a little bit. she didn't. so i said, i'll show you what it looks like then. >> and show her he did. the hilarious visuals have gone viral, giving parents, teens and even martin's daughter, cassie, something to laugh about.

>> a lot of parents can relate to it. because their teenage daughters, teenage sons, they'll take selfies all the time. >> they say a picture is worth a thousand words. but these selfies are priceless. >> there's been so many people posting, oh, father of the year. like, this is hill hair yus. like, dad goals. >> as for selfie dad, he's just glad his joke on his daughter is making others smile. >> there's just so many bad things going on, it's just something dumb to laugh at, you know? take you away from it. so if i can make somebody laugh in japan or australia or whatever, that's great. >> you certainly had us laughing. thank you for watching abc news. tune into "good morning america" tomorrow. as always, we are online at abcnews.com and on our "nightline" facebook page. good night, america.