this is "nightline." tonight, terror on the tracks. new details on the crash that turned a crowded commuter train into a lethal inferno at the height of rush hour. killing at least six and sending hundreds of passengers scrambling for their lives. tonight, the survivors and the question everybody wants answered -- why was that suv right in the path of an oncoming train? and the searing and extremely personal debate over whether or not to vaccinate your child. amidst that spreading measles outbreak. we're there as two families struggle to decide what they think is right for them and doctors weigh in on how you can keep your kids safe. ♪ bootylicious no more.

beyonce's strict new diet and the extraordinary steps she's taking to get her fans to eat like her. first, the "nightline 5." ♪ >> welcome to the most social car we've ever designed. the all-new nissan morano. nissan. innovation that excites. >> number one in 60 seconds.

and good evening. they were just trying to do what

most of us do every day, get home from work to see their families. but rush hour turned into a fiery nightmare when a packed commuter train leaving new york city slammed into an suv. tonight we're learning about how the electrified third rail penetrated the lead car of that train. we're also hearing stories of survival and hanging over it all, the mystery. why was that driver out there on the tracks? here's abc's linsey davis. >> reporter: as the crane lifts the charred wreckage of a black suv, the apparent culprit in yesterday's fiery metro north crash, the train still smoldering nearly 24 hours later as questions swirl tonight about just what caused the deadliest accident in the new york commuter rail history. >> basically, the big question everybody wants to know is why was this vehicle in the crossroads? >> reporter: it started like any ordinary commute home.

the express metro north train departed from grand central terminal at 5:44 p.m. roughly 45 minutes later -- >> report an explosion on the tracks. >> reporter: the train, rolling down the tracks at 58 miles per hour approaching a railroad crossing. just at that moment according to accounts a black suv tries to cross. but the gate comes down stopping it. the train, unable to slow down keeps coming. rick hope was in his vehicle just behind that black suv. >> the gate came down and hit the back of the car in front of me. she was trying to make it to the other side. >> reporter: the driver has now been identified as ellen brody, a mother of three from edge mont, new york. >> i'm waiting for her to back up and she moves forward. and she moved forward probably 15 feet right in front of the train. >> reporter: brody and her car were struck by the train, pushed 1,000 feet down the track, dislodging the electrified third rail. >> the third rail as we call it penetrated the chassis of

the automobile came out sort of over the right rear tire and upward at an angle, and then into the first rail car. >> reporter: the collision fueled by gasoline from the suv, triggering a fire so hot it melted the windows off the side of the train. >> doas in the train as well. >> i thought it had burned completely. i couldn't even imagine how many people were in there that lost their lives. >> reporter: chris gross was a passenger in the first car. >> i was jolted out of my seat. >> then what? >> flames. i saw people behind me in the car falling over each other. >> we skidded. skidded for i guess a couple hundred yards. as we hit that things started to at least appear to fly in the car. maybe it was sparks shooting off. it was just a lot of devastation. it was sort of hard to understand, given what had

happened. just destruction. >> reporter: ellen brody perished in the crash. as did five metro north passengers riding in the first car of the train. 12 others suffered injuries. >> it was a massive fireball yes? >> yes. >> so what saved you? >> well -- a little bit of quick thinking. one of the guys that fell on top of me burnt his hands. but he's okay. he broke the emergency latch. then i pulled the door open hopped out helped people out. people were yelling for a fire extinguisher, to call 911. a lot of yelling, a lot of screaming. you know, crying. >> reporter: there are more than 209,000 railroad crossings in the united states. in 2014 there were 2,068 incidents between cars and trains that killed 239 people. >> that's why you have crossing gates and flashing signals, the train blows its horn. all these warnings. some people just think that they

can beat the train. >> reporter: while we still don't know why the suv stopped on the tracks yesterday in a similar incident one woman says she simply froze. >> when i realized that there was just no way my car was going to make it off those tracks i think i pan i guessed and went into shock. >> reporter: betsy duvall had what i called the freeze response. unable to act, paralyzed by fear. thankfully a police officer was nearby. >> get back, come on get back. >> he said, you need to get out now because there's no time a train is on its way. all i could do was turn and watch it hit my car and just shove it down the tracks. just to think that in an instant, my life could have been just taken. without any warning. >> reporter: even with all the safeguards to warn people, accidents are still common. and can be catastrophic. in nevada an amtrak train carrying 220 passengers collided with a tractor-trailer.

>> there was a lot of smoke so we decided to stick our head out one of the doors and saw that the train was fire. i'm getting out of here. >> it was like a bomb exploded a war zone it was crazy. >> reporter: two killed, more than 100 injured. in midland, texas, four people were killed and 17 hurt when a train crashed into a parade float carrying wounded veterans in 2012. while these accidents are horrific, usually passengers inside the train are safe. yesterday was different. >> serious lyer usually it the occupants of the train. we intend to find out what makes this accident different that caused this to be fatal to five people on board that train. >> reporter: federal authorities are looking for answers to many questions about this crash. could the suv driver have gotten out of the way? why was the explosion so ferocious? and just what role did the electrified third rail play in the fatalities? >> what we intend to do is to put together that very play by

play. we want to put together a timeline to understand. one of the things we'll be doing too is a sight distance test. if you were stopped on the tracks, at what point would you be able to see a train? and at what point constitute engineer of theen could the engineer on the train be able to see a stopped vehicle? >> reporter: tonight all those questions so far unanswered. for "nightline" i'm linsey davis in new york. next, with the cdc saying all the evidence shows the measles vaccine is safe and effective, and that not vaccinating your kids might spread the disease why are some families struggling with the decision? later on "nightline," beyonce's new diet. and why she doesn't want you hitting up the 7-eleven anymore. i'm angela and i quit smoking with chantix. my children always wanted me to quit smoking but i resigned myself to the fact that it wasn't going to work. but chantix helped me do it.

along with support, chantix (varenicline) is proven to help people quit smoking. it gave me the power to overcome the urge to smoke. some people had changes in behavior, thinking or mood hostility, agitation, depressed mood and suicidal thoughts or actions while taking or after stopping chantix. some people had seizures while taking chantix. if you have any of these stop chantix and call your doctor right away. tell your doctor about any history of mental health problems, which could get worse while taking chantix or history of seizures. don't take chantix if you've had a serious allergic or skin reaction to it. if you develop thesector right away as some can be life-threatening. tell your doctor if you have a history of heart or blood vessel problems or develop new or worse symptoms. get medical help right away if you have symptoms of a heart attack or stroke. decrease alcohol use while taking chantix. use caution when driving or operating machinery. common side effects include nausea trouble sleeping and unusual dreams. i'm a non-smoker. ask your doctor if chantix is right for you.

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a very personal look tonight at the debate that is looming over the growing measles outbreak in america. you're about to meet some parents weighing the pros and cons of vaccinating their kids. should these people have freedom of choice? or are their decisions endangering the rest of us? my "nightline" coanchor juju chang on the front lines tonight. >> how are you doing? >> reporter: arianna johnson is worried. not about her 3-year-old son's lingering cough -- >> good. another one. oh, bless you. >> reporter: but rather, that it might be more serious. the measles. >> on the phone you were concerned because there's

measles going on? >> reporter: so concerned they called in their pediatrician for a house call. the johnsons live in affluent orange county, ground zero for the largest outbreak in recent memory sweeping the nation. >> i tell people if anybody's concerned about rash or measles or anything it's good to do a house call. i don't think it's the measles. >> reporter: little smith doesn't have measles. a disease essentially eradicated in this country, but now we surging. a spike of 102 cases confirmed in 14 states already this year. the american academy of pediatrics and most doctors blaming the trend among some parents saying no to vaccines. the so-called anti-vaccer movement which believes vaccines can be harmful, creating frustration in the medical community. >> we need every child to be protected against measles with vaccines so that one individual child who maybe didn't get full immunity will still be protected. >> reporter: and confusion for some parties is are asking should we or shouldn't we vaccinate?

>> it's a hard decision to make as a mother. >> reporter: the johnsons are among a growing number of parent hot have been hesitating. >> her parents vaccinated, my parents didn't. and so to -- to kind of get rid of that belief is a little bit tough. >> it may potentially harm my child. >> reporter: but now with this outbreak they're reconsidering their stance. >> i just want to be able to do what's best for my children. >> reporter: the cdc believes the outbreak began in mid december when a sick visitor went to disneyland. it spread this week in santa monica, one baby with measles shut down an entire day care center leaving 14 babies in quarantine for 21 days. >> the baby was contagious while in the child care center before a fever broke and a rash started. and the parent was concerned. >> my baby is too young to be immunized. i feel we're at everybody else's mercy until he's old enough to get his own shots. >> reporter: rules vary from state to state.

some public schools allowing exemptions for religious or personal beliefs. that santa monica day care remains closed and just today health officials warning parents, once the school reopens, all parents must show proof of protection from the measles. all this prompting some doctors to refuse treatment to unvaccinated patients. >> my office has a very strong vaccine policy. >> reporter: it's not as harsh as it might seem. it's standard practice for dr. levine, a pediatrician in new york, and member of the american academy of pediatrics. >> if a parent chooses not to vaccinate their child, not only are they putting their child at risk for preventible diseases but they're putting other children in the community at risk. >> reporter: not all doctors are drawing such a stark line. >> i do not say i will release you from my practice if you do not choose to vaccinate. i actually continue the conversation. >> reporter: orange county pediatrician iman barr practices holistic and integrative medicine. many of her patients chooses not to vaccinate and she doesn't

drop them from her practice. >> with such a highly contagious airborne virus isn't it unethical to be on the fence? don't you need to be strongly advocating for them to get vaccines? >> it's not my role to force people. >> reporter: that's the controversial approach she's taken with many families in her care, like the baileys, who held off vaccinating their infant son. but mom eileen says she was also influenced by high-profile celebrity mops like jenny mccarthy who told cnn vaccines can be harmful. >> without a doubt in my mind i believe vaccinations triggered evan's autism. >> i remember jenny mccarthy coming on tv and claiming that the vaccinations caused autism for her son. and that has been really just something that has scare med to my core as a mom. >> reporter: many anti-vaccers clung to a now widely discredited 1998 report linking vaccines to autism specifically the mmr vaccine for measles. the report was later retracted and the researcher lost his

medical license. mccarthy has since softened her stance, saying she's not anti- anti-vaccine but has concerns about the safety of some. >> science has won the debate. it's overwhelmingly clear that vaccines are safe effective, the best way we can protect our children conveyance preventible illnesses. we need to shift the tide from fear to parents feeling good about the decision to protect their children. >> reporter: two days after the house call, the johnsons have more vaccine questions for dr. barr. >> the one that is like for the brain, you know, concerns -- there's like 1 in 1 million. >> no vaccination today. >> maybe another day? or probably not? >> maybe -- maybe another day. i think that we'll continue to do a bit more research. >> a lot of people calling orange county the ground zero for the measles outbreak. does that concern you at all? >> the numbers are still -- low enough where it's not so much a

concern for us. >> my kids are in jeopardy with kids that aren't vaccinated. and i don't know anybody that doesn't vaccinate their kids. >> but then aren't you benefiting from everybody else doing the right thing? >> you know, that's a good question. yes, definitely obviously. i'm benefiting from that. but i'm not trying to fly under the radar. >> reporter: the baileys, on the other hand, have had a change of heart. >> i'm really relieved that i got it done now. we can have peace of mind that he has that first barrier of protection now. >> reporter: and the fact is the medical community is essentially unanimous that the measles vaccine is not just good for the baileys, it's good for everyone. for "nightline," i'm juju chang in orange county, california. up next how to eat like a queen. beyonce's famous for being flawless. but can you get a body like this if you sign up for her new meal plan?

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flawless like queen b, now we can eat like her with her new vegan nutrition plan. >> any time beyonce does anything, the world watches. >> reporter: inspired by the 22-day nutrition challenge, she and jay-z took on in 2013 the superstar teaming up with her personal trainer marcus boarhead to create their 22-day meal service, delivering organic, gluten, soy, and dairy-free meals to your door. >> why is hollywood crazy about the vegan diet? >> many of us are noticing celebrities that are following a vegan diet and they're seeing some weight loss benefits that come with it. >> reporter: beyonce's not the first celebrity to market it to the masses. >> you let that cook about ten minutes -- >> reporter: gwyneth paltrow was the original guru. >> i lost weight i had so much energy. >> reporter: it's not without criticism. in an interview with vanity"vanity fair" jennifer lawrence called gluten free dieting the new cool

eating disorder. there's always been pressure to stay slim in hollywood and the rest of us desperate to know their secrets. >> marilyn monroe ate a glass of warm milk with two raw eggs in it in the morning. and then at around 10:00 p.m. at night she'd have a huge hot fudge sundae. >> reporter: author rebecca harrington decided to try the quirkiest celebrity diets in "i'll have what she's having: adventures in celebrity dieting." >> victoria beckham followed the five hands diet. which involves eating five handfuls of protein a day. ten diet cokes a day, follows a 1,200 calorie diet. i think when celebrities get involved with these companies it boosts their image. they want healthy eating they want the good vibes that come with a business that can change people's lives. >> reporter: now that you can eat like beyonce, would you want to? >> we're talking about a diet that's rich in very healthy foods. >> reporter: experts say veganism alone isn't a surefire

slimming solution. >> this idea that for 22 days you guarantee i'll have a beyonce booty body by spring? only if you're watching your calories. >> finally, a sneak peek at a provocative story that will be airing here tomorrow about fresh-faced kids flocking to l.a. with dreams of stardom. they're not trying to become singers or actors as my colleague nick watt found out. these people have a more shall we say hands-on approach to finding fame. >> eight guys and eight girls will compete for porn stardom and a $1 million prize. >> reporter: the most amazing thing about exfactor is no one's thought of it before. >> a reality porn competition of never filmed before future stars. >> i mean, who doesn't like having sex with beautiful women? >> reporter: meet the brains of this operation. >> are they actually going to have sex on camera? >> absolutely. they actually already had sex on camera to audition.

>> good grief. >> part of the casting process. >> educational television right here on "nightline" tomorrow night. thank you for watching abc news. tune in to gma first thing in the morning. as always we're online 24/7 at abcnews.com. thanks again for watching. and good night. [dramatic music] ♪ ♪ >> yeah! hey! hey, hey, hey! [cheers and applause] thanks for joining us. i'm terry crews. welcome to millionaire, including all of you out there who watch my other show, brooklyn nine nine. [cheers and applause] today's returning contestant

has been a massachusetts firefighter for 19 years. let's see if he can continue to take the heat today. please welcome daniel ciccone from leominster, massachusetts! [cheers and applause] >> hey! >> hiya! how you doing? all right, let's go. >> wow. >> let's go. >> you are one of the few men who's ever picked me up before which is a wonderful thing. >> well, i'm a patriot fan terry, so, you know, that's how it is. >> that's how it is. >> that's how it is. >> well, listen, what are you gonna do with the money that you've won so far? >> well, terry i only have one child-- i know you have five children... >> yes. >> and i respect that-- my daughter's 22. she's going to nursing school and i want to try to help her out. and my son-in-law's a marine and he's coming home to the east coast, so they're setting up their family. so i want to help them. >> that's good. well, let's do it. let's do it. [cheers and applause] just to recap, you are still battling your way through round one. >> that's my bank. >> you banked $36,000. >> that's my bank. >> all right, and you are eight questions away from the million dollars. >> whew. >> and you still have two lifelines remaining. >> two l