. welcome to "world news tonight." let the medal count begin. the first gold in rio and it belongs to team usa. an opening day hitch. lines so long people waiting for hours. tonight security on high alert as olympic dreams are made and dashed. thpo new protests, a teen in the stolen car killed. tonight what police say officers may have done wrong in this very moment. concert chaos. two of raps biggest stars on stage. a barricade breaks and fans plunging several feet collapsing on to the concrete below. dozens hurt. inside the nation of north korea, a bird's eye view and a heavily

they say they are ready for war with america. and the driver tailgating so close she doesn't see what's on the road. the highway spinout with a big lesson. how close is too close? good evening and thank you for joining us on this saturday. i'm cecelia vega, we begin in rio where team usa already has gold in hand and we are talking about the very first medal of these summer games. the celebrations have not stopped. that opening ceremony. a stunning display of color and fireworks. the american athletes entering the stadium to roaring cheers and carrying the flag swimmer michael phelps, the most decorated olympian of all time. but tonight it is a first time competitor who has brought home the first gold. american shooter ginny thrasher. matt gutman starts us off in rio with the victories inside

ceremonies fireworks had barely dimmed before the first u.s. gold today. ginny thrasher turned out to be a giant in the games first competition, the ten meter air rifle. the virginia native had never picked up a fun until five years ago. tonight she's toting gold. in the pool, the u.s. men's 400 meter freestyle and women's medically competing for glory. katie ledecky. choppy waters for olympic organizers. fresh off these images of water falls in stare wells and unfinished bathrooms. crowds bunching in the heat for hours. lines not moving and manometers not working. the real organizers apologizing

also acknowledging a stray bullet hit a tent housing media at an equestrian event and a bomb squad detonating a suspected device at the fine issue line of the road race. it turns out it was just lost luggage. abc news imbedded with the bomb squad all day. showing us this controlled explosion and we learned why they are so skittish here. >> grenades, domestic need i say. >> this stuff is very common? >> yeah. >> every day? >> yes. unfortunately. >> but security person saying for these games it's not the gangs they're concerned about but a possible lone wolf attacker. it's one reason they're flooding this city with nearly 100,000 security personnel. cecelia. >> matt, thank you. we'll turn to chicago where there's growing outrage over new video of a police shooting. this moment officers shooting at a stolen car later killing the teenage suspect and it is now coming under fire by police.

police duties and tonight the department's top boss explains why. alex perez is in chicago. >> reporter: tonight, for the first time since the release of those heart racing chicago police videos, the city's top cop is speaking out. >> what i can say is that i was concerned by some of the things that i saw in the videos. >> reporter: those videos showing officers firing their guns as they pursue car robbery suspect paul o'neal. >> what is the policy when it comes to officers firing their weapons if the suspect or person involved is not firing at them? >> our policy clearly states that we're prohibited from firing into, or at moving vehicles if the vehicle is the only use of force. >> reporter: the suspect seen crashing head on into a police cruiser and then fleeing on foot.

with o'neal handcuffing him after ab officer shot him in the back. o'neal later died from his injuries. >> any member of the community is in danger. >> reporter: missing from the videos, bodycam images of the fatal shot. while authorities investigate why that critical moment was not recorded, peaceful protestors and o'neal's loved ones demanding justice. >> no one should go through anything like this. >> reporter: the family has filed a civil rights lawsuits against the chicago police and the three officers involved. cecelia. to a frightening scene in new jersey. two popular rappers in the middle of their show. you can see the crowd pushing toward the stage when a barrier collapses. fans plunging down to the concrete below. dozens rushed to the hospital.

>> reporter: cheers turning into chaos mid-concert when a barrier breaks, sending fans off a ledge. >> reporter: rappers snoop dogg and wiz khalifia on the stage in new jersey when the guardrail gives way. fans closest to the stage falling several feet, slamming into the concrete below. >> there were four or five people on top of me and it was so hard to breathe. i couldn't move. i thought i was dying. it was so scary. >> reporter: first responders say that's a six to eight footdrop off. from this angl fans flipping over and landing on top of each other. >> there's multiple patients here and they're starting the triage process. >> reporter: paramedics rushing more than 40 to the hospital. >> i saw my friends ankle and literally you could see bone. you could see like tendons. it was terrifying. >> reporter: witnesses say the crowd was pushing before the railing gave way. >> all these people started rushing crazy. >> concert promoters say they're working with structural

went wrong. wiz khalifa tweeting today hope everyone from last night is all right. live nation saying concerts will go on as scheduled. tonight donald trump is back in new hampshire, a state whose senator he just endorsed after refusing to do exactly that. trump giving two other big endorsements to house speaker paul ryan and arizona's john mccain. but is the new found push for party unity too little too late? abc's devin dwyer reports from the campaign trail tonight. >> reporter: a campaign reboot. donald trump changing course and sticking to the script. >> i support and endorse our speaker of the house, paul ryan. >> the endorsement of the nation's top republican is an olive branch to party leaders who are outraged by trump's performance.

do a lot of wonderful things. >> even trying to heal a rift with senator john mccain. he once said this. >> he's not a war hero. >> but now. >> i hold in the highest esteem senator john mccain and fully support and endorse his reelection. >> reporter: trump endorsing new hampshire republican senator kelly aott as he visits her state. three endorsements three days after he defiant lip refus give them. >> does these endorsements matter? >> no, i don't think they do. no. i don't think they matter at all. >> what did you think when you saw him endorse paul ryan? >> i just that he did the right thing for the party. >> tonight a fresh attack on hillary clinton for this. >> what i told the fbi which he said was truthful is consistent with what i have said publically. so i may have short-circuited it.

explanation why she mischaracterized the fbi investigation tweeting anybody whose mind short circuit is not fit to be our president. trump is reaching out to republicans and some keeping their distance. senator aott's office saying she appreciates his support but won't be appearing with him here in her home state. >> tomorrow morning the former cia director who called trump a threat to national security will be a guest on "this week." to severe weather. monsoon rains headed for the a downpour in the phoenix area caused instant rivers. this one so powerful it ripped away part of an iron fence. some roads flooded so quickly. drivers trapped in the mud. tonight flash flood watches are up in two states. next to a headline in the battle against zika. another new case contracted from mosquitoes, the 16th right here in the united states. the battle to contain the virus taking to the skies.

for expectant mothers on the ground grows. abc's eva pilgrim has the latest from miami. >> the growing number of zika cases in miami met with an air assault. this plane armed with pesticides for the first time taking aim on mosquito eggs in the zika zone north of downtown miami. the city of miami going around and vacuuming up water out of the drains hoping to get r grounds for mosquitoes. florida is one step closer to adding another weapon to their arsenal. the fda approving the use of genetically modified mosquitoes to fight zika. >> it mates with the female and the off spring does not develop into an adult. dies before adulthood. >> little comfort to expectant moms like fabiola surena 22 weeks

it's it's frustrating not knowing what it could do without prevention. this week hope as the first pregnant woman in puerto rico infected with zika gave birth to a healthy baby girl. >> i know she's going to be fine. she looks so perfect. >> zulmarys is one of more than 600 mothers in puerto rico. with zeke where the cdc estimates 10% of the population is infected. cecelia. >> overseas brussels still shaken after the deadly airport attack back in march. this time a man shouting god is great in arabic used a machete to attack two police officers. a third officer shot and killed. the attacker. the motive is still under investigation. next, north korea a determined enemy of the united states. just this week the u.s. imposed new sanctions and north korea conducted a new missile test. bob woodruff was right there and

tension, access never allowed before. to view the capitol from this soviet chopper, from the square famous for the military parades to the bridge to the smoking power plant. driving two hours south we arrive at the demilitarized zone. here's the line. on the other side is south korea. >> north korean soldiers on one side and american on the other. one of the top officials give us in more than a decade, just hours before we meet reports of a missile launch. just this morning the south korean joint chief of staff saying north korea launched another missile into the sea. off the east coast. what's your reaction? he says they're payback for u.s. sanctions which he calls nuclear blackmail. >> said this is a declarations of war. the united states will have to

what is that price? he says americans detained in north korea will be treated with the laws of war. people like the 21-year-old given 15 years hard labor for the theft of a sign. any communication going on between your country and ours? >> no. >> zero? >> before we depart director general hahn insists north korea won't dismantle any nuclear as he thanks us for our visit. bob rode woodruff abc news news. >> next, a victory in the battle against a legendary band of jewel thieves. this time the pink panther gang caught red-handed. here's abc's jennifer ecleston. >> reporter: high stakes jewel heists, the smash and grab gang making off with millions in minutes. not this time. handcuffed by police, five

panther gang arrested in barcelona. police tipped off, able to catch the kroox in the act. their sledge hammer left behind. $400,000 worth of rings, bracelets and gems recovered. the master criminals pulling off 380 jobs in 30 countries since 1999. netting $370 million in loot. >> i'm sorry. >> the gang's name inspired by this scene out of "the return of the pink panther" when they hide loot in a jar of face these guys have done the same thing. here the real life pink panthers crashing luxury get-a-way cars into this dubai mall. $2 million in jewels gone in two minutes. and this man calmly snatches $100 million in gems from a luxury hotel in the south of france. authorities say the panthers have hundreds of members but the special unit dedicated to taking them down is winning the battle against the world's most audacious jewel thieves.

>> still much more ahead on this saturday. a disaster in the making. are you guilty of it? tailgating. what happens next to this driver. it will make you think twice before you do it again. and the serious moment for beach-goers at a popular summer vacation spot. ? ? ? it's easy to love your laxative

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ent while you eat. so it's not about keeping my dentures in, it's about keeping the food particles out. try super poligrip free. a rollover crash. the cause, tailgating. so many of us have done it. lauren lyster tells us why we should probably all give it up for good. >> reporter: this car caught on camera careening out of control. the horrifying high speed accident. tonight a graphic display of the dangers of tailgating. watch again. the driver in the green ford quickly reacts to avoid a mattress on the road, abruptly

the next lane, then those rocks on the left, flipping across this arizona interstate. the driver, 23-year old briana disaia of texas - miraculously walks away unscathed. her life saved because she was wearing her seatbelt. arizona authorities say she was driving too close to the vehicle in front of her and didn't have enough time to react to the mattress. how long does it take to respond? >> a total of a second and a half to see something react appropriately. >> that doesn't sound like much. does it make a difference? >> it can when you're traveling at high ee half means that you may have covered 100 feet or so in that time that your brain is processing this. that's precious distance you have lost. >> a rule of thumb, give three seconds of following distance. to measure, find a fixed object like a telephone pole. when the car in front passes, count one 1,000, two 1,000, three 1,000. when you get to the marker before three, you're too close. police saying tailgating doesn't save you time, that

greater role. >> thank you. when we come back. could the key to a national health problem be hiding in the homes of the amish? the medical headline tonight. remember her? scary lucy. that's what we called her. when this turns into this. why "i love lucy" fans are smiling tonight. i accept i'm not 22 i accept i do a shorter set these days. i even accept i have a higher risk of stroke due to afib, a type of irregular heartbeat but i won't play anything less than my best. so if there's something better than warfarin, i'm going for it. eliquis. eliquis reduced the risk of stroke better than warfarin, plus it had significantly less major bleeding than warfarin... eliquis had both... that's what i wanted to hear. don't stop taking eliquis unless your doctor tells you to, as stopping increases your risk of having a stroke. eliquis can cause serious and in rare cases fatal bleeding.

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people to avoid three beaches because of a shark threat. great whites were spotted feeding off a dead whale off the shores there. to a health headline. could the amish hold the key to preventing asthma? their rates of allergies and asthma much lower and one study found dust in their homes may hold the secret. scientists are asking whether it could be linked to bacteria in barnyard dust. remember this one. i promise. "i love lucy" fans outraged at how this statue looked nothing like her. tonight a replacement. a new sculpture revealed in western new york. all seven feet of her. some calling this one loveable lucy. the old statue called scary lucy has been relocated to another part of the park. next, going for the gold like never before. the team of athletes with no home. team refugee in the olympics for the very first

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? ? ? it's easy to love your laxative when that lax loves your body back. only miralax hydrates, eases and softens to unblock naturally, so you have peace of mind from start to finish. love your laxative. miralax. finally tonight, the swimmer who used her olympian strength to save others. a refugee have a home country but she sure has a lot of guts. here's amy robach. >> reporter: a team of refugees without a home country competing in the olympics. yusra mardini stepping on the world stage. to ring applause. it was a crowning moment for the 18-year-old swimmer and refugee from syria. not far from her mind, 18 other syrians who wouldn't be alive today if not for her and her sister sara. last august they were on a small boat meant for six heading for

>> after half an hour or 15 minutes, the motor stopped. >> reporter: she and sara jumped into the water pushing the boat to land taking three and a half grueling hours in open water. >> it would be ashamed that we would die in the water and we're swimmers. >> she began swimming in damascus. >> sometimes you can train and you can see like the roof. >> reporter: after surviving she and her sister settled in germany finding a coach and a mission. go to the olympics and tell the world that refugees had to leave their homes not because they wanted to, but because they had to. this afternoon another incredible moment for yusra on the olympic stage in the 100 meter butterfly placing first in her heat. even though she fell short today she'll compete on wednesday and has another shot at olympic glory. cecelia back to you.

and thank you for watching.

>> dr. bello: coming up... 'american medine today' > this week on 'american medicine today' we visit the orlando heart health institute and see how two florida doctors have advanced telemedicine by developing a smartphone attachable stethoscope. then we speak with dance instructor diane morgan who after suffering serious back injuries is now back to life teaching dance thanks to the exclusive patented bonati spine procedures. finally dr. bonati speaks with number one new york times best-selling author dinesh d'souza. they discuss his latest book