Tonight, late word of an arrest. Plus, who will carry the American Flag in rio . The big reveal amid the urgent warning about the water. Good evening. And we begin tonight with new reporting after that crashlanding, a boeing 777 smashing down onto the runway. It would appear the landing gear was not down. Cell phone video showing the plane then skidding to a stop in dubai as smoke pours out. And then, suddenly, an explosion. The jet engulfed in a huge fireball. Passengers had just escaped. And these new images tonight of the chaos inside the cabin, as passengers raced to the emergency chutes. 300 passengers and crew then running from the flames. And tonight here, two major questions. Did the pilots forget to engage the landing gear . And was it the control tower that noticed something was terribly wrong . Just as we also learn, its happened right here at a major airport in the u. S. , as well. Abcs david kerley, leading us off. Reporter this, the final seconds of the crashlanding, with no landing gear deployed. As the boeing 777 slides down the dubai runway, its right engine ripped from the wing. Smoke billowing and then moments later, that right wing, without an engine explodes. That is the fuel tank in the wing, blown into the air, in a ball of flames. Before that fireball ignites, i was panic inside the cabin. Even though it is an emergency evacuation, some passengers are opening bins, grabbing their luggage. Jump, jump. Leave your bags behind reporter before, as we see in this cell phone video, sliding down the emergency chutes. But look, the left engine is on fire, too. The passengers and crew scramble away from the smoking jetliner. Remarkably, all survived. A firefighter on the ground was killed. All of it terrifying for the passengers. It was a big noise. We had not heard any announcement or anything. But it was a big noise. Reporter emirates flight 521 had a normal flight from india to dubai, with 282 passengers and a crew of 18. Six of the passengers americans. As the jet approaches, no sense of emergency from the pilot. Cleared to land onetwo left. Emirates 521. Reporter there are reports that the pilot was told to go around. But seconds later, the massive jet hits the ground and slides. The mystery tonight, why did a widebody jet crash land without its gear down . Former ntsb investigator in charge tom haueter says the passengers were lucky to escape, before the wing blew. Smoke then explosion. Absolutely. Its very dramatic. And that piece of metal got away, probably several thousand pounds being tossed in the air like that. Reporter emirates and dubai officials suggest there was wind shear at the airfield. The airline would not even confirm that the landing gear was not deployed, even though they did receive a digital download of the black boxes. David . David kerley tonight. David, our thanks to you. And lets get right to our aviation expert, john nance, a veteran Airline Pilot himself. And john, as you heard david report there, it would appear the landing gear was not down. You flew a prototype of the 777 before it was in service. A lot of people assume the planes are so automated now, but the landing gear, the pilots have to do themselves . Absolutely they do. Even with all the electronics, the airplane will not put its landing gear down for you. You have to do that. It will squawk at it, it will tell you you retarded power without the gear. Ultimately, youve got to put it down. Theres a chance peer the pilot similarly forgot to put the gear down . It is possible they forgot to put it down. It was 12 seconds, as you heard there, john, after this jet was cleared to land, and then the tower urging them to go around. Is it likely the tower saw the gear was not down on this jet . I think theres a high likelihood. It could have been a traffic conflict, but what is in front of us right now is the tower making a call for no apparent reason. If they saw no gear on this airplane, that would have been a reason. And john, you told me before that this has happened in the u. S. At Newark Airport . Yeah, it has. About four years ago. We gave an air Traffic Controller an award for it. He picked up the microphone, saw the 747 with no gear, said, air india, check your gear. It trundled in position and locked just seconds before it would have touched and did touch the runway. Averting possible disaster there. John nance with us tonight. John, thank you. In the meantime, we turn next here to major new developments in the race for the white house. Several Top Republican leaders are growing increasingly concerned that Donald Trumps campaign is in trouble. Amid reports of turmoil inside the campaign. Just a short time ago, what donald trump said after talk of that turmoil, amid a new poll just out tonight. Take a look. The fox news poll released just a short time ago showing Hillary Clinton now with a tenpoint lead, 49 to 39, the biggest lead in months. So, how is trump reacting to it all . Abcs david wright is in florida. Reporter tonight in florida, donald trump insists his campaign has never been stronger. The campaign is doing really well. Its never been so well united. Right now, its the best, in terms of being united than its been since we began. Reporter and from his campaign manager, this the candidate is in control of his campaign. Reporter but Republican Leaders see a campaign imploding. Theyre furious that instead of attacking Hillary Clinton, trump lashed out at the grieving parents of a fallen soldier. I was viciously attacked, so i think i have the right. Reporter and pointedly refused to endorse House Speaker paul ryan. President obama is now pressuring republicans to withdraw their endorsements. There has to be a point in which you say, this is not somebody i can support for president of the united states. Reporter some prominent republicans are doing just that. Among them, hue let pack ard Ceo Meg Whitman announcing today shes voting for clinton, saying trumps candidacy has exploited anger, grievance, xenophobia and racial division. And now, with clintons poll numbers rising, the billionaire is doubling down on this warning. Im afraid this election is going to be rigged. I have to be honest. Reporter offering no proof, trump is now predicting rampant voter fraud. People are going to walk in, theyre going to vote ten times, maybe. Who knows. Theyre going to vote ten times. So, im very concern and i hope the republicans are going to be very watchful. Reporter some Trump Supporters are now openly telling him, rein it in. You have one person to attack Hillary Clinton. Dont run against the world. He has got to find a way to slow down, really learn some new lessons. This is a little bit like the apprentice. David wright with us live tonight, and david, last night here, donald trump saying he is, quote, not ready to endorse House Speaker paul ryan, with ryans primary just days away now. Causing an uproar within the party. Has trump changed his mind tonight . Reporter apparently not, david. But today, his inning mate broke ranks. Governor mike pence, a former congressman, did endorse ryan, calling him a longtime friend and a strong conservative leader. Pence said he did talk to trump ahead of the endorsement, and said that trump strongly encouraged him to endorse him. David . David wright at a trump rally tonight. David, thank you. And all of this comes amid questions over what donald trump said women should do if theyre sexually harassed in the workplace. Abcs cecilia vega now with what ivanka trump is now saying, as she defends her dad. Reporter tonight, Donald Trumps own comments about Workplace Sexual Harassment causing yet another controversy. It began when trump defended former fox news boss roger ailes, who resigned after several women claimed he harassed them. I can tell you that some of the women that are complaining, i know how much hes helped them and now all of a sudden they are saying these horrible things about him its very sad. Reporter and then, when asked, what if ivanka trump was harassed at work . Trump saying in a recent interview, i would like to think she would find another career or find another company if that was the case. Suggesting that the victim is the one that should leave the job. Eric trump defending his father you should certainly take it up with Human Resources and i think she definitely would as a strong person. At the same time, i dont think she would allow herself to be subjected to that. Reporter from foxs megyn kelly kelly, a oneword response. Sigh. The republican nominee telling the washington post, its a womans choice to stay on the job or quit, saying, i think a lot of women wouldnt want to stay in a place where they are being harassed. Ivanka trump stepped in to try to clean up the mess. I think Sexual Harassment is inexcusable in any setting. Harassment . General, regardless sexual or otherwise, is totally inexcusable. If it transpired, it needs to be reported and it needs to be dealt with on a company level. And cecilia vega with us live tonight from colorado. And cecilia, Hillary Clinton speaking a short time ago there, she did not bring up this Sexual Harassment controversy, is that part of their strategy now . Reporter it is, and its a strategy that seems to be let donald trump do the talking, especially in the wake of this rocky 24 hours, but david, you can bet that these controversial comments will come back to haunt him in a campaign ad against him very soon. David . Cecilia vega with us tonight from colorado. Thanks, cecilia. Next this evening, to breaking news. Authorities say possible homegrown terror stopped in its tracks. An American Police officer whose job it is to keep the subway safe, the metro in washington, d. C. , is now, tonight, charged with trying to help isis. Was there a possible terrorist within their own ranks . Abcs mary bruce on the undercover operation. Reporter tonight, Law Enforcement investigating one of their own. A transit Police Officer accused of trying to help terrorists. A loner in this tightknit community. No, im not shocked that hes involved with terrorism. Reporter not shocked . Not shocked at all. Im not shocked because he was so weird. He was just so secluded and kept to himself. Reporter 36yearold Nicholas Young arrested at work today, and in court within hours. The first cop charged with aiding isis. Hundreds of thousands of people ride these trains every single day, under the careful watch of officers like young, but Officials Say young never threatened the d. C. System. He allegedly sold prepaid phone cards to an undercover fbi agent posing as an isis operative. It sounds like the fbi have been watching him for the better part of six years. Reporter Officials Say young was part of a radical network he previously associated with amin el khalifi. Seen in this undercover fbi video, readying an attack on the u. S. Capitol. Mary bruce, abc news, washington. Mary, thank you. And next here, to the Tropical Storm late today upgrau upgraded now to a hurricane, and the new track at this hour. Hurricane earl forming in the caribbean, just a short time ago. Also tonight, were tracking a dangerous new wildfire roaring to life near californias wine country. Mandatory evacuations for homes under way. Meteorologist rob marciano tracking both, and rosb, lets start with hurricane earl. Reporter yeah, its a category 1 storm. Winds of 75 miles an hour. Scraping the coastline of honduras. It will make landfall around midnight tonight. The main threat is going to be a lot of rain. Could see devastating mudslides in the mountains there. We have flash flood watches for the southeast and north carolina, seven inches of rain there, and the desert southwest. The monsoon continues. Red flag warnings in the mountains. And a tornado watch out now for parts of north dakota. But all eyes in Central America tonight, are certainly on hurricane earl. David . Rob marciano with us tonight. Rob, thank you. The Major International headline at this hour. And its an issue that will likely blow up on the campaign trail. Donald trump already asking, how this happened. There are new geoff larevelatio the Obama Administration delivered cash to iran, just as iran was releasing four american hostages back in january. Tonight, the administration denies it was ransom, so, lets get right to abcs Martha Raddatz. And martha, if it wasnt ransom, what was it . Reporter well, the white house insists the timing is a coincidence, but david, that 400 million payment, first reported by the wall street journal was delivered on an unmarked private plane using foreign currency stacked on pal lets, arriving in tehran within 36 hours of the release of those american prisoners. And within hours of the formal implementation of the iran nuclear deal. And martha, the u. S. Maintaining tonight that it was pun owed iran from an arms deal long ago . Reporter yes, from before the revolution in 1979. And that 400 million was just the first payment of a 1. 7 billion settlement, but whether they were owed it or not, david, the timing of the repayment allows the iranians to say they got something from the americans for the deals they made. All right, Martha Raddatz tracking this live from washington. Martha, thank you. Next tonight, to rio. The Opening Ceremony for the olympics just two days away now, and tonight, there are lingering fears about the water in which athletes will be competing. Abcs chief medical editor dr. Richard besser, traveling to rio to test whats in the water. Reporter tonight, the water around rio under the microscope. The World Health Organization is sounding the alarm, for some 1,400 olympic athletes set to compete in these polluted waters. We took a look from the air, where we could see the pipes directing, were told, untreated sewage straight into the water. But up close, garbage, debris and worse. Heres something you see all over rio. Raw sewage zreeming into waterways that lead out to the bay where they are holding a lot of the olympic events. Thats a big health concern. In that sewage, viruses, bacteria, that can cause severe infections. The w. H. O. Now telling athletes to cover open cuts, wash immediately after exposure and minimize their time in the water. Olympic officials insist the water is safe. But to see for ourselves, we collected a sample in two different spots and took them to a lab outside rio. And dr. Besser with us tonight. Rich, as we await the lab results, likely tomorrow night right here, in the meantime, the warning already from the World Health Organization that you just reported on, telling athletes to avoid swallowing wa water, avoid open cuts in the water, thats alarming. Reporter that is alarming. You know, you would not expect that athletes coming to the olympics would have to take those precautions. But these arent typical games. The athletes this year are going the be competing in what we think is close to raw sewage. All right, dr. Besser with this and the results on the way. Rich, thank you. There is still much more ahead on world news tonight this wednesday. The discovery behind the supermarket. Two teenagers, and now the murder mystery this evening. Late word of an arrest tonight, as an entire community now mourns the loss. Well have more on the late breaking developments right after the break. Also the major headline tonight involving michael phelps, on the eve of the rio olympics. And the Empire State Building, about to be lit up tonight for one very famous singer. Youve been listening to him for decades, hes celebrating a big birthday, any guesses . And tonight, what he revealed to us about his secret all these us about his secret all these years. Ich you are you . Be the you who doesnt cover your moderate to severe plaque psoriasis. Be the you who shows up iat dress. Who hugs a friend. Who is done with treatments that dont give you clearer skin. Be the you who controls your psoriasis with stelara® just 4 doses a year after 2 starter doses. Stelara® may lower your ability to fight infections and may increase your risk of infections and cancer. Some serious infections require hospitalization. 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