Are they the greatest of alltime . Nightly news from rio begins right now. Announcer this is nbc nightly news with lester holt reporting tonight from the olympic summer games in rio. Good evening, from the olympics. Full coverage of the headlines from here ahead, but our top story is back home where the death toll and is rising because of the devastation in louisiana. The number of rescues has reached 20,000 after a Staggering Amount of rain, as much as 2 1 2 feet inside 72 hours in some places. From overhead, baton rouge this evening, were looking at a watery scene that is in some ways reminiscent of the aftermath of katrina. Nbcss Gabe Gutierrez is in louisiana with the latest. Of louisiana under water, now a federal disaster area. What are we looking at right here . Once a shopping center, and clearly a major retail area here is compromised. Reporter today a break from the downpours, but not from the heartbreak. Many rivers receding, but still at record levels. More than 20,000 people have been resc in the past few days, more than 12,000 or so have spent some time in emergency shelters. Life after the historic flood wont be the same. In the hard hit town of watson after being pounded by 34 inches of torrential rain, the loss is staggering. Basically we lost everything other than our lives. Reporter mark mccully barely escaped with his wife and kids as the relentless river rose quickly. In a couple of hours, we probably had six foot of water. Water is probably one reporter his son blake with his own harrowing story. We were trapped. Reporter rescued separately by a coast guard helicopter just in time. You dont know helpless until youre fighting for your life. Reporter now the tropical moisture spreading west and north, putting 20 Million People in six states under flood watches. Parts of missouri and texas have already flooded. Its acting just its grabbing all of that moisture from the gulf of mexico and continues to drop it as torrential rain along the gulf coast. Reporter in louisiana, communities cut off for days are assessing the unthinkable damage. Pastor michael luces church with the sanctuary where the terrified homeowners were trapped on the second floor. Tonight he is grateful to be alive. Adding to the disaster, many homes are not covered by Flood Insurance and bit more rain is in the forecast through wednesday. Lester . Gabe, were watching another terrible disaster of a very different kind. Its unfolding in the opposite end of the country, in california where this evening nearly 9,000 firefighters are battling eight large wildfires that are burning. Theyre being fueled by scorching temperatures, bone dry conditions and strong winds. N nbcs joline kent takes us to the wildfires. Reporter out of control and burning fast. The socalled clayton fire ripping through main street of lower lake, a town founded in 1858. More than 1,000 firefighters battling flames on the ground. And in the air. Leaving wilted skeletons of homes and shops behind. I was here when i see the flames coming. Reporter as these 175 structures decimated across 4,000 acres. The devastation is huge, the devastation is extensive and there are hundreds of homes and buildings and structures that have been lost as a result of the fire activity yesterday. Reporter the local kachbd candle warehouse up in flames, now reduced to glass and black char. Barnes has lived in lower lake for more than 20 years. Grabbed the cats and grabbed the dog and basically ran for our lives. Reporter all this devastation just a few miles from the historic valley fire last year. It was the third worst fire ever in california. Its the last thing we wanted to have happen, really its just tragic. Reporter out here in lower lakes, the the fire still very much on the move, just 5 contain and the cause still unknown. And you can feel the lateday winds picking up and this could send the fire in new directions and fast. Lester . Here in rio, a lot of news to cover, both on and off the field of play, a scare at the olympic park outside the basketball venue when a tv camera from the Olympic Broadcasting Service fell 60 feet from a cable above that snapped. Injured. Also two fires burns a few miles from the olympic field hockey venue that kicked up smoke and ash that landed inside the field hockey venue. And a pair of athletes who just might be the best ever in their respective sports. We get the latest from nbcs stephanie gosk. Reporter the race is less than 10 seconds, but the usain bolt show just keeps from the very moment he walked out, to well after the race was over. This is not just about jamaica loving you, its about the world loving you. Why is that . Its just my charisma, you know what i mean . Reporter yes, its pretty clear what he means. Compare that reaction to this. U. S. Sprinter justin gatlin, banned from beijing in 2008 for doping finished second. I could see everybody so i was hi i took my time, i could see him, and i knew that i was catching him. One thing my coach always says, dont panic, take your time. Reporter bolts start was the second slowest, but then by the halfway mark, enough ahead to give a cheeky look. Usain bolt is unstoppable. At 65, he typically takes 41 steps to other runners 43. Which means each of his strides is nearly now im 58 and im not even close. And i probably cant get up. Now bolt has a record three consecutive golds in the 100 meter dash. He will race two more times here in rio. Dominance asserted on the track, while in gymnastics, dominance slipped for simone biles. If you think about it, im the only gymnast out here that s myself props for that. Reporter instead of gold on the beam, she won bronze. Teammate laurie hernandez, silver. Allison felix is going to race in the 100 meter. Thats one full lap around the track. Shes hoping to repeat her gold medal performance in london. A busy day on the campaign trail today, donald trump and Hillary Clinton both in Battle Ground states. Trump unveiled his new immigration proposal, something he called extreme vetting while powered help in going after trump. We have it all covered starting with nbcs katy tur. Reporter tonight Donald Trumps message is clear. Hillary clinton policies launched isis on the world stage. Reporter under democrats, isis is expanding, under him that will end. Trump is outlining new details for his controversial new muslim ban. I call it extreme extreme vetting. Reporter the vetting including what trump calls a cold war era ideological test. We must screen out any who have hostiles a attitudes towards our country. Reporter trump also calls for using warning signs for international intervention. This new system will be used for local Police Officers, federal investigators and immigration screeners. Hes saying a majority of americans are going to want to set aside some civil order to fight a more aggressive war against terrorism. Reporter notably missing trumps past insis tense that president obama founded isis, his attempt at sarcasm, joe biden says has no place in politics. It gets repeated in the middle east and puts a target on u. S. Troops. If my son were still in iraq, and i say to all those who are there, the threat to their life has gone up a couple clicks. Reporter trumps message on isis questions over his campaign chairmans business ties in the ukraine. The Anticorruption Task force uncovered a ledger allegedly documenting 7. 12 million in off the books cash payments. From ukraine to paul manafort. Manafort called the allegation silly and nonsensical. Scranton, where Hillary Clinton is going after donald trump where hes strongest, with White Working Class voters. Trump is counting on them to give him his best and perhaps only shot at the white house. Clinton today bringing along scrantons hometown here row to make his case, even stopping at his childhood home. If youre worried about your job, then theres only one person in this election who will possibly help you and that is Hillary Clinton. Were going to make the biggest investment in new good paying jobs since world war ii. Repr telling me trumps economic plan doesnt add up. He has no notion what hes talking about. And just look at his budget. Reporter what do you say to white, not College Educated men in pennsylvania, in scranton . Thats what im saying here, take a look at the facts, take a look at what hes talking about. Reporter clinton is practically camping out in pennsylvania. Its where the democrats held their convention, launched her bus tour, and ahead among White Working Class voters, trump is up and gaining. So we went to a diner to find out why trump. He should have you decided who youre going to vote for . Im going to vote for trump because i think he can by jobs back because hes a successful businessman. Donald trump knows what it is to run a business, he knows how to make the economy grow. Reporter clintons fix, a big dose of joe biden. Tonight we have a rare look inside a secret operation saving lives in war torn syria. Its an underground hospital hidden away as the brutal conflict between Government Forces and rebels wages on above. And so many patients brought here are children. Our Richard Engel takes us inside where some of the images may be disturbing to watch. Reporter the syrian governmentled bombing of aleppo has still working have been forced below ground. Nbc news was granted rare access to one of these unmarked hidden basement clinics, where 2yearold bayon was barely alive after an air strike on his home. Medical staff tirelessly tried to push and pump life into the boy. Then listen for a heart beat that wasnt there. But theres no time to take in the horror, children Keep Streaming in. After bombings in this city, rescue workers often save children first, so its children who fill nearly every bed. The images never leave you, they scar you. Reporter dr. Samar atar is a surgeon in chicago, but last month, he snuck into exhausted, theyre trapped, if theres a message to relay to the world, its that they want the world to know whats happening. Reporter the makeshift hospital rooms are crowded. It can take days for families to find their injured sons and daughters. 10yearold sawad lost her leg, she had been sleeping by a window when a bomb dropped. The doctor asked if any of her relatives were hurt. She says no, but shes wrong. She doesnt know that the attack that took her leg, also killed her 8yearold brother. A boy nearby repeats, he wants to leave. But theres no leaving aleppo, its encircled, starving and under attack. The injured children forced under ground. Richard engel, nbc news. And that nightmare continues. Theres more ahead as we continue, violence in the streets, fears of another dangerous night in a major American City where protesters demand to see a tape that allegedly shows Police Killing an armed suspect. Also whats in their wallets, the parents. Take viagra when they need it. Ask your doctor if your heart is healthy enough for sex. Do not take viagra if you take nitrates for chest pain or adempas . For pulmonary hypertension. Your Blood Pressure could drop to an unsafe level. To avoid longterm injury, seek immediate medical help for an erection lasting more than four hours. Stop taking viagra and call your doctor right away if you experience a sudden decrease or loss in vision or hearing. 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Were back now with tensions erupting in milwaukee, a curfew has now been imposed for teens this week after 14 people were arrested, one person was shot and several officers were injured during protests last night. Driving it all, a Police Officer who shot and killed an alleged armed suspect. Both the officer and the suspect are africanamerican. Reporter two rounds of violence, gun fire and destruction in milwaukee and tonight with more fears of more unrest, no let up in the demand, release the body camera footage. The video shows 20yearold silvil smith on foot, running away from a traffic stop, raising what appear his hand, and then a black Police Officer still unnamed firing two fatal shots. We want them to release the tape so we can see it. Because i these theyre hiding something, taking too long. Reporter after swearing in 40 new Police Recruits today, this has been a very challenging weekend for the Milwaukee Police department. Reporter he too wants that body cam video replaced. The clip was recorded without audio lasts only 25 seconds. I did not see the video, i saw the still individual in which the individual had a gun in his hand. Reporter but wisconsin state Officials Say they cannot release the video because its key evidence in their case against the shooter. Police tweeted photos of gunshots fired at them, a police riot helmet graced by a bullet last night, an Armored Vehicle hit repeatedly. It leaves concern that people shoot of whether they injure or kill them. Reporter which leaves a heightened anxiety here tonight as riot police may again have to enter this neighborhood. Kerry sanders, nbc news, milwaukee. Up next, a new warning about the health risks of something most of us do every day. Liever stops wor, your whole day stops. Try this. But just one aleve so live your whole day, not part. With 12 hour aleve. I thought my bladder leakage meant my social life was over. 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They have and not much credit, spooked by what they saw during the financial crisis. A new report from the American Heart Association claims no matter how much exercise you get, sitting too long can harm your heart. The report shows that American Adults sit between 6 and 8 hours a day and its even longer for adults 60 and over. The advice, sit less, move more with at least 30 minutes of vigorous exercise per day. Coming up next, tom brokaw takes us to a place here in brazil dont let dust and allergens get between you and lifes beautiful moments. Flonase gives you more complete allergy relief. Most allergy pills only control one inflammatory substance. Flonase controls 6. And six is greater than one. Flonase changes everything. . What body aches . What knee pain . What sore elbow . Advil liquigels make pain a distant memory nothing works faster pain . Advil. My bladder leakage made me feel like i couldnt be the father that i wanted to be. 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