alarming rise on the road, what you into he had to watch out for. thank you for joining us. "olympic zone starts here at 7:00." breaking news tonight from rio. golden girl. simone biles wins the all-around gold for the usa and aly raisman takes silver. a dazzling display as american katie ledecky blows the competition out of the water. and tonight it's phelps versus rivalries of all time. deadly explosion. a major rescue operation after fire rages through an apartment building. dramatic escapes and a frantic search for the missing. roller coaster horror. a child plunges off a ride in pennsylvania days after shocking incidents at a water slide and a ferris wheel at other parks across the country. and dangerous debris. an alarming rise in crashes caused by

free. drivers dodging missiles on the road. "nightly news" begins right now. this is "nbc nightly news" with lester holt. reporting tonight from the olympic summer games in rio. good evening here at olympic park, it is gold and silver for team usa tonight in women's gymnastics. most coveted title, the al rookie simone biles seemingly unaffected by the pressure of high expectations just delivered a jaw-dropping performance here to take the gold medal. with fellow american aly raisman taking the silver. we caught up with simone biles just a short time ago. >> i'm feeling like a whirlwind of emotions, excited, happy, proud, of both me and aly because we both went out there and we both

off her win here this evening. nbc's miguel almaguer has more on an exciting day and an exciting night to come here. >> reporter: simone biles left little doubt from the beginning. >> i don't think there's anybody else that can do this vault like simone just did. >> reporter: the 4'9" gymnast standing tall, leaping to new heights. on the floor, the vault, the beam and the bars. tonight crowned the all-around olympic champ. for the americans, gold and silver. aly raisman springing to the podium, too. biles moments ago. >> we just kept telling each other to have fun, it's only one more routine. and i think that's what we did. >> reporter: in gu wanna bar ra bay, the belgian, a sailing front-runner has fallen behind after falling ill. her coach says she got an infection while training in the polluted waters last month.

safe. in the time trial kristin armstrong took home gold and won the hearts of millions with this special mother and son embrace. >> when you become a mom, there's no reason to give up your goals and your passions and your dreams. >> reporter: in the pool, the americans needed wonder woman to come to the rescue after falling behind in the 4x200 relay. >> australia, i believe, has the lead right now. >> reporter: the australians had a nearly one-second advantage, a lifetime in the pool before katie >> and you can see it already as she's just swimming right there with her. >> reporter: surging through the pool, ledecky needed only 50 meters to catch the aussie. >> and ledecky has the lead with 100 meters left. >> every person in this pool is scared to race katie ledecky. >> reporter: with each stroke ledecky builds on her lead pulling away in a sprint that wasn't close in the end. >> ten meters left for katie ledecky of the united states. >> reporter: ledecky

ahead. >> the u.s. women win gold in the 4x200. >> that's a part of history. we're all just so happy to be a part of it and just soaking it all in. >> reporter: tonight the shine of a champion who in history stands alone. in just a short time over at the aquatic center michael phelps and ryan lochte will face off in what will likely be their last head-to-head showdown. they had one ofhe american history. all eyes on the pool. we told but the two pools that turned green. today they're still green. >> still green. all right, miguel, thank you very much. no easy transition as we turn back home now to silver spring, maryland. a suburb outside washington, d.c., where an investigation is under way tonight as the cause of a deadly apartment building explosion. authorities say it was felt as far as a mile away. people jumping to safety. nbc's hans nichols is there where the search

>> reporter: the explosion came just before midnight at these three-story garden apartments in a predominantly central american community in silver spring, maryland. as the fire raged for two hours, ladders hoisted to windows first by neighbors then firefighters. survivors spoke of dramatic escapes. children and adults leaping from the second story. >> oh, lord. >> county police on scene. advising people trapped on second and third floor. >> reporter: the force of the blast twisting and bits of balcony across the street, some 70 yards. people confirmed dead, and firefighters hospitalized. as many as 100 people displaced and several missing. >> good lord. that looks like a plane flew through it. >> reporter: today the shell of the building still smoldering. maria esperanta heard the explosion and when she returned the floor beneath her son collapsed. she hasn't seen him

the cause of the explosion unclear. officials acknowledge they received a call late last month about the smell of gas at the complex but today said any connection is premature. >> we're not prepared to discuss at this time any causes of this incident. >> reporter: this afternoon the rescue operation looking more and more like a recovery. reporting for nbc news from silver spring, maryland. for the third time in less than a week in this count c has been involved in a horrific accident on an amusement park ride. this time a 3-year-old boy suddenly plummeted from a roller coaster at a park outside pittsburgh where he's hospitalized tonight. nbc's blake mccoy has details. >> reporter: just after noon thursday, excitement turned to panic when a child fell from a roller coaster at the idlewild and soak zone theme park in ligonier, pennsylvania. >> is this child on the ground? did you move him? >> reporter: the 3-year-old said to be

children's hospital in pittsburgh. the accident happened on the rollo coaster ride. it requires a child to be at least 48 inches tall but only 36 inches if they ride with an adult. how the boy fell out is unclear. >> our rides are inspected daily, and we're not going to go into that right now, but safety is always our number one priority. >> reporter: the accident on the 78-year-old wooden coaster comes just days after three girls were injured on a ferris wheel in nn turned over. sunday a 10-year-old boy was killed in kansas while riding what's been billed as the world's tallest water slide. doctors caution some rides can be unsafe for children simply because they're young. >> they're impulsive. there are examples of children trying to climb out of moving roller coasters at small amusement parks just because they get frightened. >> reporter: but an industry association points out the chance of injury is about 1

state inspectors are on site right now helping to determine what went wrong. as for that 3-year-old, he was conscious when brought here to the hospital and tonight his family is asking for privacy. lester? >> all right, blake mccoy, thank you. a grieving husband is speaking out to nbc news after his 73-year-old wife was shot dead accidentally by a police officer in florida during a training drill gone horriblyon about how this could have possibly happened. the victim's husband tells us he saw it all with his own eyes. here's nbc's kerry sanders. >> we've been married 55 years. >> reporter: gary knowlton today mourning the loss of his wife mary. on tuesday just moments after this photograph was taken, he witnessed in horror as his partner of 55 years was shot to death by police

>> i was maybe ten feet away and watched her get shot. >> reporter: the tragic accident happened during a shoot/don't shoot citizens academy class like this one where the gun would normally be loaded with blanks, marker rounds, but how could real bullets end up in the weapon? experts say a revolver like the one used in the florida tragedy should have been equipped with sizing collars to prevent li being loaded. >> if the collars were inserted in the revolver only the training ammunition marking or blank would be able to fit in that firearm. >> reporter: officer coel on paid administrative leave has faced controversy before. a man was mauled by his police dog for about two minutes. he wasn't sanctioned but did receive additional screening. coel and his police union did not comment today but tonight mary

>> people make big mistakes and they shouldn't have to live with it for the rest of their life. >> reporter: kerry sanders, nbc news, miramar, florida. let's turn to presidential politics today. a new day and a new transfers for donald trump who over the last 24 hours is speech after speech and interview after interview has repeatedly asserted that the president of the united states, barack obama, is, quote the founder of isis and trump is not backing off those comments. even when given a nbc's hallie jackson has the latest. >> reporter: his hyperbole hitting new heights. >> isis is honoring president obama. he is the founder of isis. >> reporter: after accusing the president of founding the terror group tonight, true to form, donald trump's not backing down. >> he's the founder of isis. >> i call president obama and hillary clinton the founders

>> reporter: many conservatives argue the obama administration's actions in the middle east created a vacuum of power that let isis flourish. >> you meant that he created the vacuum, he lost the peace. >> no i meant he's the founder of isis. i do. he's the most valuable player. i give him the most valuable player award. i give her too. >> but he's not sympathetic to them. he hates them. >> reporter: the founder of isis is this man, abu president obama has conducted more than 11,000 strikes against isis and spent more than $8.5 billion fighting the terror group. >> it's about changing the storyline immediately and relying on stage craft. and that's what donald trump did today. >> reporter: hillary clinton's campaign slamming trump for his, quote, unprecedented lack of knowledge. in the mid of what "time" magazine today calls simply a meltdown. trump so far sticking to the strategy that got him this far. >> i just keep doing

in the end it's either going to work or i'm going to, you know, i'm going to have a very, very nice long vacation. >> reporter: while trump sees political opportunity linking clinton to the president, there may be political risk in going after him so hard. nbc's newest favorability ratings show the president nearly twice as popular as trump. lester? >> hallie jackson in florida, thank you. a new study out today reveals an more car crashes are being caused by falling debris often with deadly consequences. as nbc's gabe gutierrez reports the study says these lairoing moments you're about to see are preventable. >> reporter: it can happen in an instant. highway cargo breaking free turning into missiles. >> there it goes. >> boom. >> reporter: this mattress on a new jersey highway forcing drivers to swerve.

bursting into flames. >> i feel like it could have been so easily like prevented. >> reporter: this man was almost killed in florida when a heavy piece of sheet metal smashed through his windshield. >> i was driving on the interstate when a torpedo essentially went through the windshield and hit me in the face. there's really no reason why i should be here. >> reporter: a new aaa study finds between 2011 and 2014 dangerous debris played a key role in almost 200,000 crashes causing more than two-thirds of those wrecks involved objects falling out of a vehicle, most in the middle of the day on freeways. joe starts, a road ranger for the florida department of transportation says he's seen it all. >> the weirdest thing i found was barbecue grills, couches, brand-new furniture, televisions. >> reporter: in 16 states drivers of unsecured loads face potential jail time. >> it could be extremely dangerous. >> reporter: here in louisiana the penalty can be up to six

sure that their loads are secure by using the proper cargo tie-down straps. they can make sure those items are properly secured. >> reporter: advice, police say, can prevent a heavy load from carrying a heavy price. gabe gutierrez, nbc news, new orleans. still ahead here tonight, two words. simone biles. fresh off her all-around gold medal win with yet another astounding performance. a look at how gravity-defying moves. gravity-defying moves. big trouble for the young man cr lower back pain sufferers, big trouble for the search for relief often leads to places like... this... this... or this. today, there's a new option. introducing drug-free aleve direct therapy. a tens device with high intensity power that uses technology once only available in doctors' offices. its wireless remote lets you control the intensity, and helps you get back to things like... this... this... or this. and back to being yourself.

my belly pain and constipation? i've heard it all. eat more fiber. flax seeds. yogurt. get moving. keep moving. i know! try laxatives. been there, done that. my chronic constipation keeps coming back. i know. tell me something i don't know. vo: linzess works differently from laxatives. linzess treats adults with ibs with constipation

have more frequent and complete bowel movements that are easier to pass. do not give linzess to children under six and it should not be given to children six to seventeen. it may harm them. don't take linzess if you have a bowel blockage. get immediate help if you develop unusual or severe stomach pain, especially with bloody or black stools. the most common side effect is diarrhea sometimes severe. if it's severe stop taking linzess and call your doctor right away. other side effects include gas, stomach-area pain and swelling. talk to your doctor about managing your symptoms

we're back now from rio with what you might call the science of simone biles. how exactly does she do what she does? she makes it look easy, but for most of us, it's just not humanly possible. here's nbc's stephanie gosk. >> i would describe my style of gymnastics fun. >> reporter: fun for everyone except the gymnasts who have to compete against her. gold medalist nastia liukin and tim daggett say simone biles leaves them speechless. >> she is, by far, the best gymnast that i've ever seen. >> reporter: do you run out of superlatives? >> i've said that many times. there aren't enough adjectives. >> reporter: most gymnasts have one specialty. biles has three. vault, beam and floor. >> she's lightning

sense. she's got the whole thing and it all comes together. >> reporter: the best example is on floor when she does her signature move, the biles. >> she does a roundoff to a back handspring, then flies in the air, she does two flips in a layout position which we call a double layout. right before she's about to land she does a half turn, so then she's forced to have what we call blind landing. >> reporter: behind the perfection is power. >> a power gymnast is somebody that's able to generate tremendous force with if you're more powerful, you can fly higher, you can do more things and make it look even easier. >> and just up and up. >> reporter: which is exactly what biles does on the vault as well. >> it's jaw dropping when you watch her. i think when we slow it down in slow motion, too, you just see actually how high she goes. >> reporter: no one does harder routines, which means before she takes to the floor, biles already has the potential to score higher than anyone else. >> gymnastics is all about doing the hardest stuff possible

easy, and that's what she does. >> reporter: she does that. >> yeah, she does that. she makes it look so easy. >> reporter: that's why no one can touch her. stephanie gosk, nbc news, rio. >> absolutely fascinating. we're back in a mo i had so many thoughts once i left the hospital after a dvt blood clot. what about my wife... ...what we're building together... ...and could this happen again? i was given warfarin in the hospital, but wondered, was this the best treatment for me? eliquis treats dvt and pe blood clots and reduces the risk of them happening again. not only does eliquis treat dvt and pe blood clots. but eliquis also had significantly less major bleeding than the standard treatment. knowing eliquis had both... ...turned around my thinking. don't stop eliquis unless you doctor tells you to. eliquis can cause serious, and in rare cases, fatal bleeding. don't take eliquis if you have an artificial heart valve

call your doctor right away if you have tingling, numbness, or muscle weakness. while taking eliquis, you may bruise more easily... and it may take longer than usual for bleeding to stop. seek immediate medical care for sudden signs of bleeding, like unusual bruising. eliquis may increase your bleeding risk if you take certain medicines. tell your doctor about all planned medical or dental procedures. eliquis treats dvt & pe blood clots. plus had less major bleeding. both made switching to eliquis right for me.

i am totally blind. i lost my sight in afghanistan. if you're totally blind, you may also be struggling with non-24. calling 844-844-2424.

the young man whose stunt caused high anxiety at trump tower now faces big troubleit been charged with reckless endangerment and criminal trespass. he kept millions glued to their screens for nearly three hours as he climbed with suction cups before police hauled him in on the 21st floor. tonight macy's says it plans to close about 100 stores next year, about 14% of its stores as the nation's largest department store chain says it's trying to be more nimble in an ultracompetitive market. keep your eyes on

amazing tonight when the annual perseid meteor shower hits its peak. more than 200 meteors, double the usual rate which hasn't happened since 2009. western states will have the best view but the action doesn't start until the overnight hours. when we come back, how the u.s. women's gymnastics team is inspiring a new generation to follow inspiring a new generation to follow in their footste i'm hall of famer jerry west and my life is basketball. but that doesn't stop my afib from leaving me at a higher risk of stroke. until i learned more about once-daily xarelto... a latest generation blood thinner. then i made the switch. xarelto? significantly lowers the risk of stroke in people with afib not caused by a heart valve problem. it has similar effectiveness to warfarin. warfarin interferes with vitamin k and at least six blood clotting factors. xarelto? is selective targeting one critical factor of your body's natural clotting function.

g the risk of stroke. like all blood thinners, don't stop taking xarelto without talking to your doctor, as this may increase your risk of a blood clot or stroke. while taking you may bruise more easily, and it may take longer for bleeding to stop. xarelto may increase your risk of bleeding if you take certain medicines. xarelto can cause serious, and in rare cases fatal bleeding. get help right away for unexpected bleeding, unusual bruising or tingling. if you have had spinal anesthesia while on xarelto watch for back pain or any nerve or muscle related signs or symptoms. abnormal bleeding. tell your doctor before all planned medical or dental procedures. before starting xarelto tell your doctor about any conditions, such as kidney, liver or bleeding problems. to help protect yourself from a stroke, ask your doctor about xarelto. there's more to know. xarelto. it takes a lot of work... to run this business. but i really love it. i'm on the move all day long...

boost complete nutritional drink has 26 essential vitamins and minerals, including calcium and vitamin d to support strong bones and 10 grams of protein to help maintain muscle. all with a great taste. i don't plan on slowing down any time soon. stay strong. stay active with boost?. i worked years to get my medicare don't know where i'd be without it so when i heard about con-artists committing medicare fraud... to get a free offer or gift two, always check your medicare statements for errors these crooks think we're clueless, they don't have a clue it's your medicare, protect it

finally tonight, they have given us some of the more memorable moments here in rio including another dominating performance this evening. the u.s. women's gymnastics team certainly earning their place in history here. and now the future generation is looking up to these olympians tells us, are inspiring america. >> reporter: as simone biles powered her team to a golden moment, fans in her hometown of spring, texas, and nationwide roared with pride. >> who knows how many little girls are thinking they want to be like aly or maybe gabby or madison or simone? >> reporter: true enough, a group of budding gymnasts at chelsea piers fieldhouse in new york

adoration -- >> usa! >> reporter: -- and dreams of their own. like 10-year-old annelies, only 2 when she started, in a sport that didn't look much like her but is now more diverse than ever. do you think you could end up in the olympics? >> i do. i was inspired by them. >> reporter: she's following role models like dominique dawes. >> it does not get >> reporter: the first african-american female gymnast to take home a gold medal in 1996. in the 2012 london games, gabby douglas made stunning olympic history. >> and it's a gabby gold. >> reporter: winning the individual all-around championship. and now simone biles. soaring to new heights and changing the game. 18-year-old maya roberts couldn't be

qualifier she's college bound on a gymnastics scholarship and grateful to simone and others who helped the sport cross color lines. >> you shouldn't feel like you're not able to join a sport because of your skin color. it's a sport for everyone. so if she's able to inspire, then that's amazing. >> reporter: the changing face of the world's best gymnasts inspiring a new generation of young american girls. rehema ellis, nbc seeing some of them on the podium some day. that's going to do it for us on a thursday night. i'm lester holt. a reminder, nbc primetime olympic coverage starts at 8:00, 7:00 central with another big night in swimming and jiks. for all of us at nbc news, thank you for

lights. access. rio. >> he wants to beat me. i want to beat him. >> it's every man for themselves. >> phelps versus lock at the comes to its epic conclusion tonight. i'm natalie morales. there's going head to head. tell me about the rivalry. >> did i win? >> ho you did know you didn't win? >> cycling gold part of armstrong's journey. >> he said, mama, why are you crying? didn't you win the bike race? >> no wonder. >> takes more than rain and gale-force winds to get in the way of our olympic fishing reunion. i'm billy bush and my pal johnny