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"nightly news" begins right now. from nbc news world headquarters in new york, this is "nbc nightly news" with lester holt. good evening. we'll get to all the vp drama in a moment. but breaking news from france. just horrific scenes right now out of the seaside city of nice after a truck slammed into a crowd celebrating bastille day. french media is reporting at least 30 people have been killed and over 100 injured. and there are fears that this could be an act of terrorism. let's get right to nbc's kelly cobiella right now. what can you tell us? >> reporter: lester, witnesses are saying that a white truck hopped the curb on this famous promenade des anglais in nice at a high speed plowing people down in the middle of this crowded bastille day celebration. the french media, specifically bfm tv is reporting there was also an exchange of gunfire after that truck rammed the crowd. that has not yet been confirmed by nbc news. all of this happening towards the end of a bastille day celebration there. fireworks were going off at the time. and people absolutely panicked, running down the street. french media tonight reporting dozens dead, several injured. those numbers not yet confirmed by nbc news. there are also reports that the truck driver has been killed. again, unconfirmed by nbc. the mayor of nice and local police tonight warning people to stay inside because of what they called an attack. we don't know the kind of attack, the motive at this point, but lester, this comes eight months after the attacks in paris that killed 130 people. a very nervous night, a very scary night tonight in nice. >> you can certainly see the panic in those pictures. let me go to american journalist bob franken who is on the ground in nice, france and joins us on the telephone. what do you see where you are? >> reporter: at the moment, the promenade des anglais is very quiet and you see a few emergency vehicles moving up and down, but although a witness -- i did not see the truck itself, witnesses said that it jumped the pedestrian area, which is right along the mediterranean and started mowing down people. i immediately went out there and i counted a dozen bodies both dead and injured. and chaos. meanwhile, people had gone racing away by the thousands. this was bastille day. there was a fireworks display, as kelly said. it had just concluded when this incident occurred. the police were trying to get people to go down to the beach on the mediterranean. their concern was that there might be a follow-up of some sort. then a person said that the mayor is saying that people should stay home because their might be some sort of follow-up. >> and from what you saw and the pattern of victims in the street and what you're hearing, was there any doubt that this was an intentional act? >> well, no. no doubt whatsoever. neither the police nor witnesses said that this was anything but an intentional act, as you put it. the truck just mowed people down. there is some question about whether there was, in fact, gunfire. as i said, the fireworks displays with just ending, but the truck stopped a few hundred yards up the roadway. >> bob franken on the ground in nice, france. france has seen so much tragedy over this past year. we thank you for that report. and as develops warrant, we'll continue to update that story. we want to go to the latest developments on a big story here at home after a flurry of reports and denials and virtual tea leaf watching that sent the donald trump veepstakes into a frenzy. we have an answer tonight. sources are telling nbc news that trump has chosen indiana governor mike pence as his vice presidential running mate. the official announcement is scheduled to come late tomorrow morning. we want to go to nbc's katy tur who has late information on this. katy? >> reporter: hi, lester. sources close to the candidate and within the campaign tell me that donald trump has made his decision tonight and it will be indiana governor mike pence. this is after much deliberation as late as this afternoon there were still three contenders in the race. former house speaker newt gingrich, new jersey governor chris christie, and indiana governor mike pence. ultimately what happened was that donald trump decided that he wanted somebody who could balance him out. and tonight you're seeing governor pence come off of a plane in new jersey on his way to donald trump's new jersey golf course where he will stay overnight. tomorrow we'll get the announcement at 11:00 a.m. governor pence impressed donald trump the other night when he opened for him in indiana. sources tell me that they were expecting him to be quiet. instead he was quite vocal and quite an attack dog. why did he pick pence? donald trump said he wanted somebody with legislative experience. for many, that's pence, an evangelical christian with ties to the grassroots. a known quantity in washington like trump says he's looking for. the former congressman from rural indiana rose to one of the highest house gop leadership positions riding the tea party wave to indiana's governorship in 2013. >> here in indiana we've been proving every day that we can balance our budgets, run our schools, choose our health care. >> reporter: but now, facing a tough re-election fight. and perhaps looking for a more national profile. that comes with the trump territory. but he hasn't always seen eye to eye with the candidate. tough on immigration. he nonetheless has called trump's temporary muslim ban offensive and unconstitutional. and he splits with trump by supporting major trade pacts. a possible ticket that reflects some of the divide between the gop and its presumptive nominee. a word of warning here from sources close to donald trump. he is unpredictable. and they warn that he could always change his mind. but as of now, lester, it is indiana governor mike pence. >> all right, and katy, for more on what this means for the trump campaign, let's turn to chuck todd. moderator of "meet the press." did trump go with his heart or practicality? >> this was all about political pragmatism here. finding a midwestern governor that can help trump in the states he wants to target, the northern tier of the country. it's not about indiana, it is about ohio, michigan, iowa, all of those things. what's amazing about this pick is this, lester. it's an incredibly conventional safe pick unless you're donald trump. you could make an argument that for him doing what political advisers are pushing him to do, doing what appears to be a conventional choice is actually a very risky pick for him. it's risky for his brand, which is something he's been weighing, this idea knowing that pence is a very conventional idea, where if he picked either christie or gingrich, it's a little less conventional and more trump-like. that was a concern. is this too off brand for donald trump? at the end of the day, one thing mike pence brings is calm at this convention. don't underrate that aspect of the pence pick. making social conservatives happy probably means a happier convention in cleveland. >> you are thinking he could soothe over ruffled feathers in the republican party? >> absolutely. remember, this is a guy who endorsed cruz. so he can make that case as a former cruz supporter, i'm with donald trump. i want to unite the party. >> chuck todd. thanks very much. tonight pk spk justice ruth bader ginsburg is acknowledging that her public criticism of donald trump was a bad idea. ginsburg has been broadly criticized from the right and left from steering out of her lane by making negative quips about the republican candidate in recent print interviews, and she's now expressing her regrets, but it may be hard for her to put the controversy behind her. justice correspondent pete williams joining us to explain. >> reporter: lesseter, a surprising end to a back and forth between a supreme court justice and presidential candidate. ruth bader ginsburg today calls her recent remarks ill-advised and regrets making them. judges should avoid commenting on a candidate for public office. and she promises to be more circumspect. in recent print interviews he called donald trump a faker with a big ego and joked that she might move to new zealand if he's elected. he responded by saying she should resign and she might be losing her mental fitness. while ginsburg's statement is not an apology, she admits making a mistake and he accepts that. >> pete williams a tt supreme court, thank you. a severe weather alert as storms move across new york today. and in the midwest powerful thunderstorms blew through the region. wichita, kansas, strong winds tipped over a semi truck on the highway. gusts up to 70 miles per hour also knocked down a number of trees and power lines. now to more are of our nbc news exclusive interview with syrian president bashar al assad. tonight we hear assad blasting the u.s.-led offensive against isis inside his country. and again, this interview was filmed by the syrian presidential press office, but there have been no editorial changes to the content. here's nbc's bill neely. >> reporter: tonight from syria's leader, harsh words for president obama, calling u.s. air strikes against isis ineffective. is that a military fault or is president obama simply not being, let's say, ruthless enough? >> it's not being ruthless. it's about being serious. it's about having the will. he doesn't have the will to defeat the terrorists. >> reporter: but assad has faced global criticism for air strikes on civilian areas. blocking food for tens of thousands including children. do you ever see pictures, photographs, videos of children, for example, in rebel-held areas? and i wonder if you have seen those photographs, what do you feel, sorrow, regret, nothing? >> my question, how could you verify that those children that you saw on the internet are in that area? >> reporter: mr. president, an answer like that simply reinforces people's views that you're evading responsibility, that actually you don't care for the people on the other side that your forces kill. >> that question could be answered if you answered that question. how can you blame now bush for the 1 million iraqi dead since the war in iraq in 2003. >> reporter: i'm not talking about president bush. i'm here to ask you -- and he says he's not worried about putin asking him to step down. he claims that's never been discussed. lester? >> bill neely in the mideast tonight, thank you. still ahead this evening, driven to the edge. what a shocking number of people admit doing on the road that's linked to more than half of all fatal crashes. and which part of the country, experts say, has thes are wo drivers. also new sketches of the serial killer holding a city in fear. holding a city in fear. ♪ is depression more than sadness? holding a city in fear. ♪ it's a tangle of multiple symptoms. ♪ ♪ trintellix (vortioxetine) is a prescription medicine for depression. trintellix may start to untangle or help improve the multiple symptoms of depression. for me, trintellix made a difference. tell your healthcare professional right away if your depression worsens, or you have unusual changes in mood, behavior or thoughts of suicide. antidepressants can increase these in children, teens, and young adults. trintellix has not been studied in children. do not take with maois. tell your healthcare professional about your medications, including migraine, psychiatric and depression medications to avoid a potentially life-threatening condition. increased risk of bleeding or bruising may occur especially if taken with nsaid pain relievers, aspirin, or blood thinners. manic episodes or vision problems may occur in some people. may cause low sodium levels. the most common side effects are nausea, constipation and vomiting. trintellix did not have significant impact on weight. ask your healthcare professional if trintellix could make a difference for you. defianour citracal bones. easily absorbed calcium plus vitamin d. defy bone aging with citracal maximum. our highest level of calcium plus d. there is some troubling new research out tonight on something that many, if not most of us, have experienced. aggressive driving and road rage. aa reports it has become so common that 54% of all fatal accidents inform some form of aggressive driving. tom costello has more. >> reporter: road rage in california. a limo driver takes a tire iron to the car behind him. in florida, an irate truck driver is so distracted giving someone the bird, he loses control and crashes. [ laughter ] >> that's what you get also. >> reporter: also in florida a couple on a motorcycle run over after exchanging words at at an intersection. the driver, robert vance, now charged with attempted murder. aaa reports that aggressive driving is so common that 80% of those asked admitted they did it in the last year. tailgating, honking, rude gestures, cutting off, bumping or ramming other drivers. >> anger is a normal emotion. we all experience it. and that's okay. what matters is how we manage it. >> reporter: all too often not so well says this state trooper. >> they'll go out in traffic and run people off the road and end up throwing like maybe a bottle or something. >> reporter: nationally 4 out of 25 road rage related fatalities in 2014, up 40%. 19 to 39-year-old men are three times more likely to drive adwresively than women. in the northeast, much more aggressively, to honk, to yell and offer on scene gestures than the rest of the country. eric caldwell is charged with assault with a deadly weapon after allegedly using his pickup to ram into two teenagers sending them careening off the road. the teens survived. caldwell's attorney isn't commenting and neither is robert vance facing attempted murder charges in florida. tom costello, nbc news, vienna, virginia. we're back in a moment with a tour de france pile-up caught on camera, but it's what came next that you really have to see. before i had the shooting, burning, pins-and-needles of diabetic nerve pain, these feet played shortstop in high school, learned the horn from my dad and played gigs from new york to miami. but i couldn't bear my diabetic nerve pain any longer. so i talked to my doctor and he prescribed lyrica. nerve damage from diabetes causes diabetic nerve pain. lyrica is fda approved to treat this pain, from moderate to even severe diabetic nerve pain. lyrica may cause serious allergic reactions or suicidal thoughts or actions. tell your doctor right away if you have these, new or worsening depression, or unusual changes in mood or behavior. or swelling, trouble breathing, rash, hives, blisters, muscle pain with fever, tired feeling or blurry vision. common side effects are dizziness, sleepiness, weight gain and swelling of hands, legs, and feet. don't drink alcohol while taking lyrica. don't drive or use machinery until you know how lyrica affects you. those who have had a drug or alcohol problem may be more likely to misuse lyrica. now i have less diabetic nerve pain. and these feet would like to keep the beat going. ask your doctor about lyrica. ...meta appetite control. you and temptation with... clinically proven to help reduce hunger between meals. new, from metamucil, the #1 doctor recommended brand. 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to find out, i'm wearing three fitness trackers on the same wrist. right here i have the jawbone up three. i have the garmin vivo smart hr and here's the fitbit hr. i walk around new york city. for more than an hour. oh, baby. ending up in central park. >> everybody is talking about them. and everybody wants one. >> reporter: we're going to see which one is the most accurate. >> oh, my god, fabulous. >> reporter: just stop walking. time for the numbers. the fitbit says i walked 5,188 steps. check the garmin. it says i walked 5,984 steps. so a lot more. but the jawbone says i walked the most. a whopping 6,271 steps. so what are you supposed to believe? >> hop up on to the treadmill. >> reporter: to find out, i came here to the performance lab at new york's hospital for special surgery. that mask measures my calorie burn. my producers count 500 steps. >> 498, 500. hop off. >> reporter: well, that's comfortable. on steps, the fitbit was the closest with 502, the garmin 520 and the jawbone 559 steps. but the real headline here is the calories, right? what is the official number from your computer? >> you burn about 19.9 calories, which is just about 20 calories in those few minutes of walking all right this is amazing. none were even close. the jawbone was the closest saying 43. that's nearly double the number. fitbit 67 calories, more than triple your number. the garmin came in the highest saying i burned 78 calories, nearly quadruple what i burned. >> not even close. >> reporter: the companies telling nbc news, the trackers are designed to motivate and encourage healthy lifestyles. garmin adding the position on the wrist matters. if multiple devices were worn at the same time and whether it's on your dominant hand. so this summer, go for a walk, go for a jog, but experts say don't expect absolute precision. jeff rossen, nbc news, new york. well, that is going to do it for us on this thursday night. i'm lester holt. for all of us at nbc news, thank you for watching, and good night. hot couples, a-list cameos and the biggest names in sports taking a powerful stand. >> we all feel helpless and frustrated by the violence. >> we're breaking news from one of the most memor memorable esp awards ever now on "extra." ♪ ♪ newlyweds russel and ciara leading a couple's invasion at the espys. lebron james leading a superstar call to action. >> i think the cops are amazing people. >> from the poignant speeches to the tribute to the greatest, our man akbar is all over the espys. >> what happened backstage that no one saw? >> plus, new video. the espy couples we spotted partying after the show. >> megyn kelly's explosive face-off with d.l. hughley. that's insulting. >> why things boiled over. >> so we're even. >> game of thrones. "the people versus o.j. simpson," "blackish," the emmy race is on. >> congratulations, anthony on your emmy nomination. >> thank you very much, and you guys have to watch it, "extra" for all your emmy nominations. >> we've got all of the nominees today. then new video, taylor's man tom hammered about the big rumors. >> is there any truth to the engagement rumors, tom? >> plus pregnancy's bringing