on this saturday night, marching on. 50 years after bloody sunday, the president retraces the steps of those who made history as tens of thousands honor a landmark moment in the civil rights movement. deadly encounter, a police officer shoots and kills an unarmed man after reports of a confrontation. tonight, the investigation and the outcry. a caffeine warning for parents. the new lawsuit that's shedding light on a potentially deadly form of caffeine. and baby boom, one of the rarest creatures in the world now making a big comeback. this is "nbc nightly news" with lester holt. substituting tonight peter alexander. good evening. what happened in sel 50 years ago is seared into the

history for this country's struggle for civil rights. it became to be known as bloody sunday. police officers violently attacked protesters marching peacefully. toda african-american president retraced those steps alongside dozens of others including former president george w. bush. president obama took a moment to look back and forward enlisting a new generation into the fight. nbc's kristen welker joins us from the bridge where protesters changed the course of history. kristen. >> reporter: peter, good evening. the energy w. it's estimated as many as 40,000 people turned out from all across the country to honor the courageous men and women who risked their lives to fight for equality and justice on this bridge 50 years ago. 50 years ago he would have been met with troopers, tear gas and taunts. today, the first african-american president clutched the hand of one of the men who made it possible for him to be here as they crossed the edmund pettus bridge, a symbol of how far america has come.

>> if someone had told me that we were crossing this bridge that one day i would be back here introducing the first african-american president, i would have said you're crazy. >> reporter: introduced by congressman john lewis, the only surviving leader of the selma march, president obama paid homage to all those who paved the way for him. >> they held no elected office. but they led a nation. >> reporter: for everyone in the crowd this day is personal. >> i've alwaysug don't know where you're going unless you know where you come from. >> i'm here for my parents and my grandmother. she probably couldn't even imagine standing here in this place. >> reporter: it's also a reminder of how painful it was to get here. it was march 7th, 1965, when a group of activists set out on this bridge to demand voting rights. and were met by an unimaginable brutality by those who were supposed to protect them. what did they do? >> they started wading in after a shock period of time.

>> reporter: beating? >> beating and riding horses. and with the tear gas it was horrible. and it was something that i don't ever want to relive. >> i was injured along with a few others. >> reporter: mary was a child when her mother viola volunteered to drive marchers home after a subsequent trek from selma to montgomery. a lot of people said it wasn't viola's battle to fight, after all she was a white mother of five. >> for her, her children having a good life involved having a better world. >> reporter: that courage cost viola her life, killed at the hands of the kkk. >> i am so proud to be her daughter. >> reporter: the daughters and sons of selma say the journey isn't over yet. with incidents like ferguson and the supreme court's decision to reverse a key part of the voting rights act, today president obama had this message for 100 members of congress who made the trip with him and those who didn't. >> if we want to honor this day, let that hundred go back to washington and gather 400 more

and together patch to make it their mission to restore that law this year. that's how we honor those on this bridge. >> reporter: a renewed call to action to fulfill a vision from 50 years ago. now, there was a small group of protesters here today. they were demanding that police reform after ferguson president obama didn't appear to hear them. meanwhile this community continues to remember tomorrow. thousands are going to turn out again. they're going to cross this bridge, one final tribute to bloody sunday. peter. >> a historic anniversary, kristen welker, thank you. tonight, there are protests over another deadly police shooting of an unarmed man after complaints of a confrontation, this one last night in madison, wisconsin. the investigation is just now beginning. and we get more tonight from nbc's anne thompson. >> reporter: from madison, wisconsin today cries similar to the ones heard in ferguson and new york. protesters out in force after last night's killing of tony

terrell robinson jr., an unarmed black man shot by police. tapes of local police transmission show the beginning of the incident as police responded to a complaint. >> look for a male black light skinned, tanned jacket and jeans outside yelling and jumping in front of cars, 19 years of age name is tony robinson. >> reporter: more police calls came in with reports he assaulted people before running into an apartment. madison's police chief says an officer followed the suspect, heard a disturbance and forced his way into the apartment where the suspect attacked him. >> shots fired. shots fired. >> 1247 copy shots fired. >> reporter: today officials identified matt kenny, a 12-year veteran, as the officer who shot and killed robinson. >> i want to be very transparent. he was unarmed. >> reporter: officer kenny the chief said was involved and cleared in a fatal shooting in 2007. kenny is now on administrative leave. >> oh, my god, they killed my grandson.

>> reporter: robinson's grandmother and aunt joined protesters at the crime scene last night telling the crowd robinson was a good person who planned to go to a technical college. they urged calm. the state division of criminal investigation now has the case as required by law in fatal police shootings. chief cobalt called for restraint in the wake of robinson's death. >> we need to make this a very public show of our remorse and contrition for his loss. 19 years old is too young. >> reporter: a loss, he described, as tragic. anne thompson, nbc news, new york. this week isis sparked new outrage by destroying more ancient remains at iraq's heritage sites. now as the iraqi forces fight to take back key cities from militants, they're finding help from an unexpected ally. nbc's chief foreign correspondent richard engel has our report tonight. >> reporter: the front line in the war on isis is inching

closer to the iraqi city of tikrit. but it's not american advisers who are helping the iraqi army move on its target. it's iranian advisers. led by this man, head of iran's clandestine force. but there's nothing secret about his presence in iraq now or about the fact that most of the 20,000 or so fighters who are laying siege on tikrit are not members of the iraqi national army. they are fighters from sectarian shiite militias. iran, according to u.s. officials, is providing them weapons, intelligence and surveillance. joint chiefs chairman general martin dempsey, who arrives in iraq next week, has said could play a useful role in fighting isis. >> if they perform in a credible way, rid the city of tikrit, turn it back over to its inhabitants, then it will in the name have been a positive thing. >> reporter: meanwhile isis is

busy destroying the region's uniquely rich cultural heritage. first, isis released a video showing its men ransacking mosul's museum, desecrating what historians call artifacts from the cradle of civilization. then reports the militants have bulldozed the ancient city of nimrud, and today iraqi officials say militants are destroying the 2,000-year-old city of hatra. >> my reaction was anger first and foremost. and rejection and condemnation of this appalling act of what we call a cultural cleansing. >> reporter: isis is trying to destroy any sign of a civilization other than its own interpretation of sunni islam. iran has its own goal, to fight isis while at the same time expand its influence in iraq. richard engel, nbc news, istanbul. two suspects have been detained over the murder of russian opposition leader boris nemtsov. he was gunned down late last week in the shadow of red

square. he was one of president putin's most outspoken critics. the kremlin denies any role in his death. back in this country some of the gop's top presidential contenders have descended upon iowa to court voters in that all important bellwether s. they're taking part in an agriculture summit, but in many ways this is about planting seeds nor a 2016 run. nbc's kelly o'donnell is in des moines for us tonight. kelly, good evening. >> reporter: good evening, peter. iowa is already vetting potential candidates for 2016. but what happened today was different. this was not a campaign-style event with stump speeches or candidates signs. instead this was a test of fluency on farm issues. and there was a lot of attention around jeb bush making his first campaign-style visit to iowa. at the agriculture summit, food is politics. >> we'll be cooking iowa beef. and i'll probably make a really good guacamole. >> reporter: everything from

ethanol to the impact of epa regulations. >> the first thing you do is you change presidents. >> reporter: many conservatives are wary of jeb bush on immigration, but he found an opening here because agriculture relies on migrant labor. bush called for a step short of citizenship. >> immigrants that are here need to have a path to legalized status. >> reporter: today's summit drew nine republicans with presidential ambitions. from neighboring dairy state wisconsin, governor scott walker separated himself from bush on immigration. >> i'm not supportive of amnesty. i respect their views on that but i'm not a supporter of amnesty. >> reporter: new jersey governor chris christie has been in iowa often and brushed off attention surrounding jeb bush. do you feel any of the jeb bush pressure? >> i don't feel it. i don't feel that kind of pressure. >> reporter: christie even cheerfully dismissed protesters from his home state. >> great to have you here. >> reporter: upset by his handling of superstorm sandy recovery.

>> i'm glad to see that new jersey has come to iowa. how great is that? >> reporter: unusual for a republican event, no mention of hillary clinton. but off stage clinton's use of only her personal e-mail account for official government business at the state department drew sharp criticism from ted cruz. >> one expects the justice department to investigate that an investigative process. >> repor did not address the issue of the e-mail usage when she was at a speech in miami. jeb bush remained here in iowa visiting some restaurants that are always must-stops on the campaign trail. his chance to really mix it up with iowa voters. peter. >> all right, kelly, thank you very much. while the controversy surrounding hillary clinton drew criticism from at least one republican presidential hopeful, it's now stirring debate among democrats, specifically for what it means for their most high profile candidate. for more we're joined by our political director and moderator of "meet the press," that is chuck todd.

chuck, this clearly isn't going away. on top of the benghazi controversy, how big of a distraction is this for clinton as she gears up for a potential 2016 run? >> obviously it's a distraction right now because we're potentially just a few weeks away from when she officially begins her campaign. she's making hires. and it's putting the structure together. right now with democrats, i mean, we've done our own polling. we'll be debuting some tomorrow and throughout the week. it's not hurting her yet with democrats. but that's not the issue that she's got to be dealing with with this e-mail business. it's the fact that it gives credibility to the republican investigations and capitol hill. and, peter, what does that mean? these republican investigations aren't going to go away. they're going to linger. and i think they're going to be very active through november '16. so when she's a general candidate at any moment some leak from capitol hill could turn into a distraction. >> exactly. chuck, thank you very much. chuck will clinton controversy right here tomorrow morning on "meet the

press". when "nightly news" continues on this saturday, it's a powder form of a substance millions of us drink every day. but now a new lawsuit is shedding light on a potentially deadly form of caffeine. and later, baby boom for one of the rarest creatures. otentially deadly form of caffeine. if you have moderate to severe rheumatoid arthritis like me and you're talking to your rheumatologist about a biologic... this is humira. this is humira helping to relieve my pain and protect my joints from further damage. this is humira giving me new perspective. doctors have been prescribing humira for ten years. humira works for many adults. it targets and helps to block a specific source of inflammation that contributes to ra symptoms. humira can lower your ability to fight infections, including tuberculosis. serious, sometimes fatal infections and cancers including lymphoma have happened, as have blood, liver, and nervous system problems, serious allergic reactions, and new or worsening heart failure. before treatment get tested for tb. tell your doctor if you've been to areas where certain fungal infections are common, and if you've had tb hepatitis b, are prone to infections,

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we're back with an update on a story we first told you about last august. it involves the use of caffeine, specifically a pure concentrated form sold as a dietary supplement. taking too much could be deadly as the case with an ohio teen.

his family is taking legal action in hopes of preventing another tragedy. nbc's john yang has the report. >> reporter: logan stiner was at the top of his class, an athlete, prom king loved by those who knew him. >> he made everybo >> reporter: just days before his high school graduation last may, logan was found dead. he had overdosed on pure caffeine powder. what do you think of this product? >> i think it should be off the market, banned unless it's in the hands of a licensed pharmaceutical company. >> reporter: logan's parents say a friend gave it to him. it's sold as a dietary supplement to boost alertness and athletic performance. >> this product kills. if you're going to continue to sell it and cause harms and losses, you're going to be held responsible in court. >> reporter: in a wrongful death suit filed friday, dennis stiner says amazon.com and other caffeine powder provided inadd

cat warning about the supplement's danger and engaged in activities including the supplying and delivering of a defective, dangerous and unsafe product. pure caffeine is. a teaspoon is the equivalent of 25 cups of coffee. if used for any reason, the recommended dose is about 1/16 of a teaspoon per day. >> when people have this powder in front of them, they can't imagine the size of a matchhead is the dose they should be taking. >> reporter: logan's autopsy showed he had 23 times as much caffeine in the system as a typical coffee or soda drinker. according to stiner's lawsuit the product's safety labeling is unclear. >> it's inadequate in terms of the dosage. it's inadequate in terms of the instructions for use. in terms of the warning or the label, it isn't there. >> reporter: nbc news reached out to the defendants. only amazon.com provided a formal response saying, we do not comment on active litigation."

logan's case is not isolated. 24-year-old wade swit of georgia died last june also from caffeine overdose. in february the stiners testified before an ohio senate committee supporting legislation aimed at getting this substance off the market. >> my message to my kids is always change the world, make it better. and certainly did that. >> reporter: as the stiners push to make their own change, one they hope will save lives. john yang, nbc news, chicago. when we come back, one family's daring escape in the face of firestorm. in the face of firestorm. hey, girl. is it crazy that your soccer trophy is talking to you right now? it kinda is. it's as crazy as you not rolling over your old 401k. cue the horns... just harness the confidence it took you to win me and call td ameritrade's rollover consultants. they'll help with the hassle by guiding you through the whole process step by step. and they'll even call your old provider. it's easy. even she could do it. whatever, janet. for

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a frightening scene in central california this morning when a party got out of control. look at these pictures. dozens of college students were standing on the roof of a garage when it collapsed during a party that took place near the cal poly campus. at least a dozen were injured. now to some incredible stories of survival. in october 2003 the largest wildfire in california history engulfed the san diego area. it tore through hundreds of thousands of acres and overtook people as they slept. in a special edition of "dateline" survivors are sharing their harrowing accounts of how they made it out alive. here's nbc's josh elliot. >> melanie was just 13. and her sister lindy 11 when they were awoken by their mother's cries of fire. >> she comes in, wakes us all up, get up, get your stuff, get

your books, go out to the truck. we have to go. >> reporter: they rushed their daughters to their truck and sped from their home in verona, california. only to find the road ahead engulfed in fire. >> and it's like, okay, what do we do. are we going to try to drive through this? will we survive it. >> i don't want to die. i'm too young to die. >> reporter: the family made a u-turn, but their truck stalled. so their only choice, leave it and run. >> we follow our parents. we put our shirts up over our mouths to try and filter out the smoke a little bit. >> the heat that night was as if you open your oven and just that gust of heat that comes out. >> after maybe five or ten more feet we told our dad, look, we can't do this, it's too hot, there's too much smoke. >> reporter: they sought refuge back in the truck. but just moments later. >> the flames start licking up over the engine, under the hood, up the front windshield. and my mom said we have to get

out. the truck's going to explode. we need to get out of the truck now. >> reporter: they ran to a dirt clearing and waited for hours until the flames finally passed. today, they know how lucky they are to have survived a fire that devoured more than 270,000 acres, destroyed more than 2,200 homes and claimed 15 lives. >> thinking back of how we survived is pure miracle, pure luck, pure chance. we're very fortunate to be here together. >> that was josh elliott reporting. you can hear more of those survival stories during a special "dateline" presentation escape the great california fire. that's tomorrow night at 9:00 eastern right here on nbc. up next, a comeback for one of the world's most endangered creatures. of the world's most endangered meet the world's newest energy superpower. surprised? in fact, america is now the world's number one

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it's a big deal. and it's how edward jones makes sense of investing. finally tonight, a baby boom, but not the kind you'd likely expect. for decades the giant panda has been on the endangered species list. but now they're starting to make a comeback. ian williams traveled to china to check it out. >> reporter: alas some good news for china's endangered giant pandas. beloved all over the world, the number in the wild increasing by a sixth over the last decade according to a survey by the chinese government. >> the it's drawing more attention.

>> reporter: researchers spent three years counting pandas covering nearly 12 million acres of mountainous forest. they followed tracks and collected evidence from camera traps concluding that 1,864 pandas remain in the wild. there are a re captive breeding programs. who could forget this famous trio? the world's only known surviving panda triplets born last summer. i got to meet the adorable cubs when they were just 2 months old. just last year 23 cubs were born, most now being raised in this facility in the mountains near chengdu. we joined them for an afternoon snack. most of kindergarten area are between a year and year and a half old. and they have an enormous appetite. here too the opportunity to be a volunteer panda keeper has brought young people from around the world who pay the breeding

center $50 a day to feed and take care of the pandas. there is one dark spot on this otherwise encouraging picture, a virus has killed four pandas at a facility in northern china. experts are holding an emergency meeting in beijing this week. encouraged, they say, by unprecedented levels of public awareness and support. >> because everybody think realize panda is vital, is worth to protect. >> reporter: for an iconic animal while not out of danger may well have turned an important corner. ian williams nbc news chengdu, china. from cuddl close the night, that's "nbc nightly news" for this saturday. a quick reminder to spring forward. for those of us who still have clocks that means setting them forward an hour before you go to bed. i'm peter alex from new york. for all of us here at nbc news, good night.

right now on nbc bay area the manhunt continues for an inmate who escaped during a doctor's appointment in san jose. he is a convicted sex offender and is considered dangerous. and a huge frat party gone

wrong. the garage they were partying on collapsed underneath them. today marks the 50th anniversary of bloody sunday. a live report from selma, alabama, commemoration of the historic march. good evening. i'm terry mcgovern. >> and i'm peggy bunker. we're on at this special time because of golf. new details on hayward's second attempted kidnapping in as many weeks. police released this sketch today of the man wanted for trying to pull a girl into his car yesterday afternoon. the 15-year-old was walking home from school when the man grabbed her without warning. a very similar incident happened on february 20th. this near the corner of ebony and joshua streets. in both cases, the girls were able to fight off the man. the man was driving a white car. the suspect descriptions have similarities but also some differences. this sketch was released after the february 20th attack. investigators are askin