this is "nightline." tonight, america in black and white. after the controversial back-to-back shootings of two black men by police officers, and then the targeted attack on police in dallas last week, we go on patrol. taking an intimate look at what it means to be a black police officer in a diverse community as america's tensions run high. going for gold. gymnastics superstar simone booils is headed to the olympics after amassing 14 world championship medals. she's favored to win almost all of her competitions. even has a signature move. what does it take to become such a sensation? and the new pokemon smartphone app that's takin

america by storm with some unforeseen consequences. first the "nightline 5." ♪ ♪ >> when you don't get enough sleep and your body aches, you're not yourself. tylenol p.m. relieves pain and helps you fall fast asleep and stay asleep. we give you a better night. you're a better you all day. tylenol. >> and number one in just 60

good evening. tonight we take you to the front lines of what is now one of the most dangerous and controversial jobs in america, police work.

focus of an intense national conversation after the fatal police shootings of black men in louisiana and minnesota, then the murder of five officers in dallas. my "nightline" coanchor juju chang gets a street-level vuitton night in this the first installment of our special week 95 long series in "america in black and white." >> 1607, 1654 -- >> 1110. >> seems like, you know, in the current climate you have to be more vigilant. >> yes, with everything going on, you have to be more vigilant. we always have to stay alert. >> reporter: officer mark blackwell knows the streets of bridgeport, connecticut, well. he grew up not far from here in a family of cops. but in the wake of the dallas ambush, this week feels different. >> do you ever think it's open season on cops? >> feels like a bulls eye on our backs right now. we all want to be able to go home to our loved ones. >> reporter: his newest loved one, his 6-week-old daughter. it was nine years

that the 44-year-old blackwell first donned his blue uniform and the badge. a badge now shrouded in mourning for blue lives lost in dallas as protests for black lives spotlight a painful racial divide. >> oh my god, please don't tell me he's dead. >> reporter: after the controversial shooting of two black men by police officers, we decided to go out on patrol with blackwell and joey agosto, two cops uniquely positioned to bridge the gap. after the deaths of alton sterling and philando castille at the hands of police, intensifying the anger towards law enforcement. now a rallying cry for nationwide protests. starting out peacefully but ending in arrest after arrest. at least 42 in new york. 19 in chicago. 102 in st. paul. one of the most prominent national leaders of black lives matter, deray

the 125 arrested in baton rouge. >> why is he being arrested right now? >> reporter: periscoping his arrest live. in st. paul alone, 21 officers were injured by rocks and bottles thrown by protesters. one officer's teeth knocked out. some condemning the entire protest movement. >> this is quickly becoming a terrorist group committing hate crimes. >> reporter: the "new york post" categorizing the conflict with two provocative words -- civil war. >> hate's not going to get you any-where. it's just fueling the fire. >> everything is cops or pigs, cops are this, all they want to do is kill people. it's not like that. >> reporter: for officer blackwell, his shifts rarely involve violent confrontation. he's never fired his gun in the line of duty. when things start to get tense they rely on critical training to defuse conflict, the best weapon for police to avoid using force.

call. an allegedly drunk man banging on a door trying to get into an apartment that isn't his. officer blackwell and augusto keep the suspect calm, convincing him to walk away, bloodied, into an ambulance. crisis averted. blackwell and augusto believe in community policing. trying to erase the perceived battle lines between people of color and the police. >> they were born here, raised here, they're part of the community. >> reporter: this isn't just friendly chitchat, to them this is quality police work. >> does it help that you're black? >> in some cases. in dealing with the public i could sometimes de-escalate a situation. >> reporter: so much of their police work is a strategic effort to stay connected to the community. today they shoot hoops with neighborhood kids, teenagers who tell us they've already had those tough conversations with their parents. do they tell you how to act around the police

they say you stop, you stop. don't run. >> do you feel the cops or good guys or bad guys? >> some cops choose to use the law for what they want to do. >> when you see teenage boys what do you think? >> even if they do something bad, i try to turn it to something positive with them. >> you have to do a threat assessment? >> correct. depending on the situation, our safety always comes first. >> reporter: bridgeport, like so many urban areas, facing its own painful questions about police brutality. this video from 2011 launched an fbi investigation. that man's lawsuit settling out of court with bridgeport police. the two officers pled guilty and were sentenced to prison. ♪ >> reporter: by sunday morning, reverend anthony bennett of a historic black church across town is hearing calls to postpone their march on the local police headquarters. >> we are tired, brothers and

sisters, of explaining to white folks and even some of our own people that being pro-black is not being anti-white. >> reporter: hundreds gather to the steady sounds of drumbeats. refusing to let one tragedy eclipse another. >> i personally, i think that everyone should be getting the message. it's not that we're disregarding any other lives, anything like that. we just need to focus more on the black lives because we're the ones being affected the most. >> do you worry black lives matters gets hijacked by a sniper in dallas? >> no. no more than what dylann roof did indicts all white male christians in this country. >> reporter: along the march an army of cell phones. many live streaming. >> we out here, hello. >> reporter: cell phones now ubiquitous, documenting the deaths of alton sterling and philando castille, whose girlfriend live streamed the

by police. >> you told him to get his i.d., his driver's license. oh my god. please don't tell me he's dead. >> reporter: these graphic images creating a groundswell of public sympathy for black lives matter. but the backlash is something officer augusto and his brothers in blue must contend with. >> people are like pretty much in your face with that, that camera. we're like, can you step back, give us some room? they don't want to move. >> we're judged on a split-second decision where the public, the media, they can analyze that, that same video, for hours. >> these are not just split-second decisions, these are life and death decisions. >> life and death, life and death. nobody wakes up to say, i'm going to come to work today and i want to kill somebody. >> integrity! >> reporter: and yet we find common ground. >> should we have education and mentorship for our young

so they don't end up living a life with police engagement? >> reporter: shared frustration over the rampart violence and needless loss of life. this is from the mass shooting? >> we had a shooting up here, people got shot, including a fatality. black on black crime is out of control. there's a lot of people in this community that want to address that issue. they don't want to see their loved ones killed. >> reporter: it may not have made national headlines but the killing left its mark on this community and these officers, who say that above all they took the oath to serve and protect in order to prevent heartache like this from happening. >> seems to me every day you go out on the job, you're putting your lives on the line. >> i love what i do. >> you love what you do? >> yeah, i'm scared. you have to be scared when you do this job. but it's what we do to protect other people. >> reporter: in the twilight hours of our ride with officer blackwell, he takes us to a place he describes as one of the most dangerous housing projects in bridgeport where shootings

>> i'm going to be a cop when i grow up! >> reporter: instead of blood we find hope. >> what are you going to be? >> a cop. >> you want to be a cop when you grow up? >> me too. >> you too? >> me too. >> reporter: hope that these young boys will never have to choose sides in a country seemingly divided between black and blue. for "nightline" i'm juju chang in bridgeport, connecticut. next, one on one with a young woman they're calling the best gymnast in the world. her extraordinary skill, her signature move, and her moving personal story. later, how a brand-new app already has more android users than tinder. why pokemon go has police in some areas concerned. doubts go. 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,

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we are coming up on the olympics and there is one name you will likely be hearing a lot. simone biles. she's a 19-year-old gymnastics prodigy. but before you see her perform in rio, you will want to hear her incredible backstory. here's abc's philip menknow. >> reporter: simone biles is doing things other gymnasts have never done. she hasn't lost a competition in three years. she has her own move, the biles. >> she flips backward with a straight body two times. on the second flip she does a half-turn and lands forward. >> reporter: yesterday she took one more step toward the one thing she hasn't yet achieved. an olympic medal. qualifying for the u.s. team going to rio. >> sometimes i hear the crowd cheering and most of the time

so sometimes even after i do a floor routine, i'm like, did i really just do that? >> reporter: 2012, simone was too young to compete in the london games. since then she's been on fire. the 19-year-old gymnast is a three-time world all-around champion, the first woman to win the title three times in a row. she's earned 14 medals in the world championships, 10 of which are gold. we sat down with her before the u.s. olympic team trials to find out what it takes to make gymnastics history. >> you know how many hours a week you work? >> 32 hours. on mondays and wednesdays i train 12:30 to 5:30. tuesday, thursday, friday, i train 9:00 to 12:00. then 3:00 to 6:00. then saturday we practice 9:00 to 1:00. >> reporter: time spent earning wins and the admiration of legendary coaches. >> today, she's the best gymnast ever. >> reporter:

simone compares to the very best in olympics gymnastics history. >> back at that time it was considered perfection, absolute perfection. mary lou in her time was considered one of the wonder childs of the sport of gymnastics. now simone's time is coming up. >> reporter: mom nelly biles says simone was a little spring from the time she was a girl. >> always jumping. always flipping. i don't think simone ever walked up the stairs. >> reporter: discovering gymnastics was an accident that happened when a field trip was canceled. >> they did an indoor trip instead and ended up going to bannon's gymnastics. and i still recall simone coming home with a note saying, would we consider her joining the gym? >> reporter: simone's biological grandparents adopted her from foster care at age

with their unwavering support simone sprouted. >> always travel to me meets and do whatever i need. i'm really grateful for that. whenever i go out and compete they're so excited when i do well. they know how hard i've put in. >> reporter: her coach remembers when she saw her for the very first time at age 6. >> i was like, what is with this kid? she did a round-off backhand spring. her very first time in class. and she said, my brother taught it to me in the backyard. so -- it didn't take long before we pulled her to have her evaluated for team. >> reporter: it's those handsprings perfected that sets her apart, says her coach. >> knowing exactly where you are in the area. some people have incredible balance? imagine having balance without your feet on the ground, while flipping and twisting, knowing exactly when you have to bring your feet to the floor so you don't die. >> reporter: not dying was what was on my mind when i tried a small fraction of what simone does every day. >> whoa. >> if he splits the bea

hurt himself. >> is split a beam what i think it is? >> yes. >> reporter: that smile and those medals have caught the attention of corporate sponsors. household names like tide pods. >> it's small but mighty. i paired up with them because it reflects on my gymnastics. i'm very small but i like to say i'm powerful. i think it went hand in hand. >> reporter: before the commercials and the fame, there was sacrifice. all those countless hours in the gym forced her to miss out on moments most teenagers cherish. >> since i was homeschooled those years so that i could do what i do, i thought that like i was missing out on like public school, going to all the football games, prom, homecoming. but then once i think back to it i'm like, well, yeah, i can say i've missed prom but i've been to three world championships. they won't ever get to say that. so i think it's a win-win. >> i know it was tough for her because she saw her friends that she grew up with going to prom and home coming and all that

any of that. i know it was a struggle. split and wrap, good. she's a major rock star. when you have people like mary lou retton and alec kroelly saying she's probably the greatest gymnast they've seen in their lives, that's a really big deal. >> reporter: but that also creates really big expectations. simone is the favorite to win gold in five the six olympic events. >> i guess what's on the line for her is it would solidify her as the best ever. >> reporter: she needs just three medals in rio to welcome the most-decorated american gymnast of all-time. >> what would you feel when you -- standing up on the podium, you hear "the star-spangled banner"? >> that's a very emotional time. you feel everything, all your hard work put into that one moment. then especially with the team you all get to share that memory together. it's something you can remember forever. >> reporter: for "nightline," philip menna in hughes

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finally tonight, why a new pokemon app is catching fire and catching the attention of law enforcement. here's abc's chief business technology and economics correspondent rebecca jarvis. >> reporter: it's the latest craze to hit smartphone users across the country. pokemon go. the new app going viral with more android users than tinder. number one in the itunes store. ♪ got to catch them all >> reporter: based off the series and playing cards, the app mixes the virtual world with reality. using the gps and camera in your phone it lets you see and catch pokemon everywhere you go. over the weekend #pokemongo trending online. gaming gurus getting in on the fun. >> i found one! >> reporter: nintendo

price soaring adding $9 billion in one week. outside of central park, looks like it is filled with pokemons. of course i had to give it my own test run. where is he? there you go. even making some new friends along the way. >> this is what i've caught so far. >> it's pretty good. those are like rare, i think. >> rare? i got three of them. >> reporter: the pokemon go craze hasn't been all fun and games. in wyoming one user happened upon a dead body while playing. in missouri authorities say armed robbers used the app's location feature to target victims. in a joint statement e-mailed to abc news, the pokemon company commenting on the safety concerns surrounding the app writing, we are aware that some incidents have occurred involving fans playing pokemon go. we encourage all people playing pokemon go to be aware of their surroundings. which is exactly what i plan to do. for "nightline," i'm rebecca jarvis trying toat

>> our thanks to rebecca, and thanks to you for watching "nightline." tune in to "gma" first thing in the morning. we're online 24/7 at abcnews.com and our "nightline" facebook page. stop it! it's mine! it's mine! that's enough fighting! everybody, that's enough. we're goin' to church. come on. oh. aw. mom. all right. ok, here. turn that off. how come daddy never has to go to church?

why don't you ask daddy? [with mouth full] i have to work, honey. see? he's eating his business lunch. i am working. there's a big game on today. i thought it didn't start until 1:00. ok, yeah, but there's a pregame. look, i don't tell you how to do your job, right? all right, everybody, let's go! church time! chop-chop. you usually hide upstairs until we leave. a little more brazen in your blasphemy. don't tell him how to do his job. come on. let's go. hey, what...? i don't know why god put church and football at the same time. as a matter of fact, bring that up today.