welcome to "world news tonight." system meltdown. hundreds of flights delayed. passengers standing in endless lines. tonight, the nationwide travel trouble. terror attack. the peace rally rocked by two powerful blasts. carnage and sorrow as officials point to suicide bombers. thousands now marching in protest. but who is to blame? caught on camera. a man on his knees, then police tase him. the man, an elected city councilman. and, inside job? a former lottery official, convicted for buying this winning ticket in iowa. his brother and friend also winning jackpots. tonight, the investigation going national. was your lottery rigged? plus, a possible cancer breakthrough. could elephants hold the key to beating cancer? the secret in their dna, and the new hope for saving lives.

good evening. thanks for joining us on this sunday. i'm tom llamas. we begin with an airline travel mess affecting tens of thousands of passengers. the trouble, with a type of airline ticketing technology. the delays rippling across the country. in los angeles, arriving on the monorail, seemingly endless lines. inside, passengers waiting everywhere in epic lines. with the work week about to begin, kayna whitworth is at hard-hit l.a.x. >> reporter: tonight, a travel nightmare for thousands as southwest airlines grapples with a computer glitch. lines spilling all the way to the curb in las vegas and denver. and a bottleneck in los angeles. tents set up to shield passengers waiting from the

heat. southwest blaming a "technology issue" affecting everything from its website to mobile app reservation centers and airports. >> sometimes murphy's law gets you, doesn't it? >> reporter: the trouble beginning around 10:00 a.m. as southwest begins manually issuing boarding passes. by mid-morning, a tweet from southwest saying, "we apologize for this morning's technical issues." adding, 150 flights were affected. >> i usually do online check-in and i couldn't do it. so, i knew something wasn't working. >> reporter: with the airline scrambling, southwest employees handing out water to frustrated passengers. by 1:30 p.m., the number of flights affected jumping to 450. passengers unsure if they'd get to their destination. are you sick of waiting in line? >> absolutely. >> reporter: last month, american airlines grounded flights in three cities because of a computer glitch. in august, an air traffic control problem caused by a software update snarled travel along the east coast. and in july, united blaming a computer malfunction for hundreds of delays. southwest says the problem is affecting future bookings as well.

i spoke with a woman who missed her flight and said no one could help her, because southwest has no access to their reservations. tom? >> kayna, thank you. next to the race for 2016 and the big week for democrats. the candidates go head-to-head in their first debate on tuesday. vice president joe biden on the sidelines. will he be running? his decision expected soon. cecelia vega on the vice president and the democratic race. >> reporter: tonight, all eyes on joe biden. is this a man in the running? biden at his grandson's football game this weekend sprinting past the cameras. dodging questions about whether he plans to enter the race. >> everyone wants to know. >> get out of my way, will you? >> reporter: after weighing the decision publicly for months. >> i'd be lying if i said that i knew i was there. >> reporter: sources now tell abc news this is the week biden will make up his mind.

a decision that will come after the first democratic debate on tuesday. on that stage, hillary clinton trying to maintain her status as the party front runner as her poll numbers dive. this weekend, she's off the trail and holding mock debates to prepare. her aides playing the role of her political rivals like former maryland governor martin o'malley and vermont senator bernie sanders. sanders gaining on clinton in the polls, pulling in nearly as much cash and drawing 9,000 people to a rally in colorado on saturday. this morning facing questions about whether he's trying to move away from his socialist label. >> when one of your republican colleagues gets on the show, do you say, "are you a capitalist?" have you ever referred to them as capitalists? >> yeah. are you a capitalist? >> no. i'm a democratic socialist. >> reporter: the big show now just two days away in las vegas. but the main attraction in this race remains camped out in delaware weighing the political decision of a lifetime. and the clock is ticking.

biden is expected to meet with his family at some point this weekend. that is going to be a deciding factor in his decision. he's here at his house in delaware through tomorrow. tom? >> cecelia, thank you. and overseas now to that developing story in turkey. the devastating attack in a peace rally. this video capturing the act of terrorism as it happens. the event shattered by the first blast. moments later, a second one. then the bodies of the victims lay covered in flags. and tonight, this vital u.s. ally at the edge of the middle east is in turmoil. alex marquardt with the story. >> reporter: youthful singing and joined hands under a clear blue sky. the peace this rally called for shattered by two blasts. many fled as fast as they could. others stayed to help the wounded. the deadliest terror attack in turkish history. almost 100 killed.

today, the site was cordoned off by police. forensics teams combing it for clues. this is as close as we can get to the scene. turkish officials say they believe that it was suicide bombers who carried out the attack, either isis or kurdish militants. but so far, there has been no claim of responsibility. thousands turned out this afternoon for remembrances. and to vent their anger at the government for allowing the attack to happen. at the hospital, families and friends waited for news in the driveway. 21-year-old ulas was just a few yards from the blasts that took the lives of 16 of his friends. he's now worried that turkey has entered a dark new chapter. do you think there will be more attacks like this in turkey? >> yes, yes, yes, it can be. >> reporter: as the country marks this tragedy with three days of national mourning, that fear over more violence is now growing, with contentious elections just a few weeks away and turkey cracking down on isis

and its kurdish enemies. tom? >> alex, thank you. and back to texas, and a police tasering incident captured on camera. the subject, a young city councilman. outside his apartment building. the officers asking him to step away. he objects, and then officers tases him. here's marci gonzalez. >> reporter: tonight, questions about this takedown of a texas city councilman tased by police in his front yard. >> put your hands behind your back. >> reporter: police body cam video shows councilman jonathan miller outside of his home thursday night, asking officers why they were questioning three of his friends. >> i'm not trying to be combative or anything. >> okay, i'm not either. >> okay, man. go stand over there, man. this is a scene. this is a scene.

come on. come on. >> please don't put your hand on me. >> go over there before you go to jail for interfering. >> reporter: the tension, quickly escalating. >> i'm telling you one more time go over there before you go to jail. turn around. >> i'm not saying nothing. >> reporter: police saying he physically resisted arrest. and mr. miller continued to do so despite repeated commands to stop. the prairie view police chief telling abc station ktrk the female officer also responded as backup to sandra bland in this same town over the summer. miller, charged with resisting arrest and interfering with public duties, now out of jail. he and neighbors, raising concerns over the male officer's use of force. >> i don't see why he should have tased him. >> reporter: those officers still on the job tonight while the department investigates. marci gonzalez, abc news, new york. now to cleveland,

prosecutors releasing two reports on the shooting death of tamir rice. both finding the police response, quote, "reasonable." it happened about a year ago, a squad car responding, within seconds shooting rice, who had a realistic pellet gun, killing him. tonight, the family's response, as the grand jury is still weighing charges. here's ron claiborne. >> reporter: the two outside experts retained by cleveland prosecutors looked at this evidence. and concluded the shooting of 12-year-old tamir rice was justified. the officer and his partner were responding to a report of someone in a park with a gun. it turned out he had a pellet gun. but a former fbi agent said, not only was he required to make a split-second decision, but his response was a reasonable one. in his report, a denver prosecutor dissected the video.

the officer firing from close range in a matter of seconds. his conclusion, the officer was in a position of great peril. tamir's family, including his mother, outraged by the reports' findings. >> ms. rice and her family now believe that this has been an 11-plus-month charade to ensure that's there's no accountability or indictment of these officers. >> reporter: a grand jury will ultimately decide whether to bring charges against the officers. but tonight, the rice family now skeptical. the prosecutor invited the family to submit their own reports from experts. their lawyer says they're still deciding. they do not trust that prosecutor. >> so many across the country following the case. ron, thank you so much. in florida, a dangerous and frightening sight. in tampa bay, a water spout spinning at the side of a bridge, catching drivers by surprise. then the funnel cloud, crossing the road. then striking a mail truck, tipping it over.

and ripping it apart. the driver escaping without injury. and in parts of south carolina, a real-life water world. thousands of families forced from their homes by the swollen rivers and broken dams, as they battle a new enemy. phillip mena reporting in from conway, south carolina. >> reporter: with waters receding, the race to save the homes. >> you tear it all out. get the house dried out, and build it back. >> reporter: volunteers helping homeowners. as the city hauls away debris. >> few get to the point where the mold grows rapidly, it could be a complete demo. >> reporter: the goal, getting the water-damaged drywall and furniture removed before mold starts growing. in the east, a much different story. here, in conway, the river is now eight feet above normal. and for the thousands living in the flood path, life is still far from normal.

>> it's hard. they've never been through anything like this. >> reporter: trips to school, work, even walmart, require a 20-minute boat ride down the street. >> i wish we could make it all go away, a plug that could make it go somewhere. >> reporter: with so many roads still impassable, fema is bringing in amphibious vehicles to help. >> we've never experienced anything like this in our entire life. >> reporter: and tom, this is one of those streets, still impassable. officials say it could take up to a month for the streets to dry out. tom? >> phillip, thank you. we want to turn to some medical news now. an exciting prospect in the fight against cancer, inspired by a trip to the zoo. a researcher there remembered that elephants rarely get cancer. and wondered if whatever protects them could save people as well. here's nick watt. >> reporter: elephants have survived 55 million years on this earth. they've evolved to beat cancer.

and they might just help us beat it too. >> in this elephant blood, i totally truly believe lies the secret to cancer prevention. we have something here that potentially can save millions of lives. >> reporter: elephant blood from schiffman's local zoo and the ringling brothers and barnum and bailey circus. you see, most humans have only two copies of a gene called p53, which kills cancerous cells. elephants have around 40. and elephants hardly ever get cancer. does this somehow then involve getting p53 genes from an elephant into a human? >> that's one approach. there are other things we can do. looking for drugs that mimic the effect. >> reporter: schiffman is inspired in this bizarre collaboration by his patients. >> i'll undergo brain surgery again in two weeks. >> reporter: a recurring cancer because tony means has only one working p53. >> i have passed it on, i guess,

to landon, emma and sophie. >> reporter: whose lives one day could be saved by tonka, mabel, luna and assan. nick watt, abc news, salt lake city, utah. >> we thank nick for that story. still ahead tonight, can the lottery be hacked? a lottery employee barred from playing. but investigators say that didn't stop him from helping others to win. how he allegedly rigged the system, and how they think it could be bigger than just one state. and later, dirty play? the bone-breaking slide the mets are furious about. those stories, coming up. when a twinge of back pain surprises him. morning starts in high spirits but there's a growing pain in his lower back. as lines grow longer, his pain continues to linger. but after a long day of helping others, he gets some helpful advice. just two aleve have the strength to keep back pain away all day.

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>> reporter: what authorities call one of the biggest lottery frauds ever. >> if you watch all five numbers and the hot ball, you win the jackpot. >> reporter: tonight is getting bigger. edward tipton allegedly rigged computers to pick specific numbers. so he could win iowa's hot lotto game. but hid his own identity. paying associates to collect a $16 million prize. >> ladies and gentlemen, we have the winning ticket. >> reporter: eventually, he was fired, convicted, sentenced, and sent to prison. but officials say he also fixed games in colorado and wisconsin. a total of $1.3 million paid to winners that just happened to be his own brother and a longtime friend. they have not be charged in this case, but that friend is facing two counts of fraud in the earlier iowa case. >> this is a breach of trust against lotteries, players,

games, and the billions of dollars at stake for the worthy causes that lotteries benefit. >> reporter: tipton's lawyer is appealing the conviction. and says the new charges are an effort to garner publicity. calling the previous case fatally flawed. but investigators say they're not done. >> this is now a nationwide investigation. that seeks to identify instances where individuals may have perpetrated fraud against the lottery game. >> reporter: the lotteries say they've now added multiple layers of new security. hoping to lower the odds of getting taken again. clayton sandell, abc news, denver. >> thank you. coming up, could kanye west be moving to the white house? why president obama says president kanye may not be a total fantasy. and this sweater, look again. it's a treasure for one family, going back generations. we'll explain.

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2020. >> do you really think that this country is going to elect a black guy from the south side of chicago with a funny name to be president of the united states? that's crazy. >> he's got a point. the president joking at a fundraiser in san francisco where west was the headlining act. now to a hand-me-down sweater that just keeps showing up in one family's photos generation after generation. the grey sweater little brady gose is wearing here for his first grade picture has been worn by five family members in their first grade picture starting with his grandfather back in 1954. brady says he plans to pass it one day to his children. when we come back, the new trend in high schools. why the homecoming court is looking so different these days. it's not about the dress, or the date, but about life lessons. stay with us. days. it's not about the dress, but about life lessons.

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finally tonight, it's homecoming season. a tradition marked by the thrill of the big game, the dance and the crowning of the king or queen. but this year at some schools, the memories will be about so much more. at the homecoming game at this pennsylvania high school, the biggest play came at half-time. the school coming together to crown a queen unlike any other. >> she just has a kind heart. always wants to brighten people's day, and she does. >> reporter: this year's queen, sarah neslun has down syndrome, but her sister says that's not why she's being honored. >> sarah didn't win because she has a disability. it's because she's a great person overall. >> reporter: in tennessee,

brayden carpenter sported this new haircut, because his date is fighting brain cancer. he just wanted to make her comfortable. and this school, making a 3-year-old girl their queen. >> it's something that immediately touched us. there are so few times in your life when you feel an immediate impact. >> reporter: the team first met her when they rehabbed her backyard, making sure she had grass to play in. she's undergone multiple open heart surgeries. her fighting spirit and the players' love for her, a true homecoming memory. >> it touched my heart, i wanted to cry, seeing her walk out being crowned queen. >> and it touched our hearts as well. "gma" first thing in the morning. david muir right back here tomorrow night. i'm tom llamas in new york. have a great evening.

breaking news in downtown san francisco. what police know about a deadly crash between a bicyclist and a bus. and passengers trying to get to china after of have to turn around over the ocean. why they're sag united dropped the bull. >> drew says really warm temperatures, perhaps record-breaking. how hot and for how long? abc7 news at 6:00 starts right now. breaking news, a bicyclist hit and killed by a bus during a busy weekend here in san francisco. happening now. police are trying to figure out how it happened. sergio quintana tweeted this photo of the bike on the ground an hour after it happened. this is on market street between

battery and sutter streets. so let get to the scene right now. sergio is there. do we know who is at fault yet? >> reporter: that's actually something that investigators are trying to piece together. this investigation is still in progress. you can see a bunch of police officers and the bicycle that was involved in this collision, also the bus that unfortunately made contact with that male rider, 47 years old. unfortunately he did not survive. he was just -- the body was recently taken away by the medical examiner. showing you some video. we're told the bicyclist was not in a bike lane or a shared lane. we're also being told that the bicyclist was riding between two buses and made contact with one of them. traffic on market was shut down immediately after this collision. people on the buses were offloaded, questioned to see if they say anything, and then put on other buses. right now investigators are