after marco rubio unloaded on trump. one of the most dramatic campaign days ever. nbc news investigates amid allegations by rubio the inside story of how undocumented workers worked at the site of trump tower. mass shooting horror. four dead, 14 wounds as a gunman opens fire at a workplace. a hero cop taking him down. tonight, what we've learned happened in the hours before the massacre. zika in america. the cdc warns of a surge in cases. the virus is now striking pregnant women here. and fairy tale ending. a little girl's unicorn on the loose, and a police chase like we've never seen before. "nightly news" begins right now. >> announcer: this is "nbc nightly news" with lester holt. good evening. what a wild day it has been. one of the most dramatic and intense days of this presidential campaign

hours after mocking, ridiculing and challenging donald trump on the debate stage, a rejuvenated marco rubio struck again today. then donald trump struck back with a surprise announcement of new jersey governor chris christie. it was all part of a nasty back and forth war of words between trump and rubio on the trail just four days before super tuesday. nbc's katy tur starts off our coverage. katy, what a day. >> reporter: lester, they say everything is bigger in texas, and this endorsement certainly came as a big surprise. less than a month after he dropped out and just four days to go until super tuesday, chris christie is getting behind donald trump and trying to lay waste to marco rubio. >> ladies and gentlemen, it is my honor and my privilege to introduce the next president of the united states, donald trump. >> reporter: donald trump added a little jersey pride to his texas swagger in fort worth today. former presidential candidate chris

front-runner. >> i really was happy with this one right here. chris, thank you. we love you, man. >> it's all make believe. >> reporter: less than a month ago, christie was trying to tear down trump. >> i never said that i could shoot somebody in the middle of fifth avenue and i wouldn't lose a voter. i never calls mexicans rapists and murderers. i never said ban all muslims from the united states. >> reporter: the new jersey governor and new york mogul both often called bullies, now teaming up to eviscerate marco rubio. >> you know, last night i thought the deal of the night was when i looked over to rubio, and i said, you remember, you're a choker, and we don't want chokers in our administration. i said, you're a choker, and you're a liar. >> reporter: trump again mocking rubio's state of the union water bottle gaffe. >> let's talk about our lightweight senator from florida. >> he doesn't have the talent. he can never make us great. >> reporter: the endorsement, perfect timing for trump after a bad debate that let

for his inheritance. a trump university fraud suit and not releasing his tax returns. >> the irs has said there's nothing precluding you in its rules from releasing your tax returns with an audit. >> until my audit is finished, very simple. you're not going to see anything. when it's finished, you're going to see it. but i'm not going to complicate things. >> reporter: christie, a cunning application whoment believed could have bridged gaps in washington, is picking the sure bet. sources familiar with the governor's news. but rubio, after standing up to trump at the debate, isn't going to go down without a fight. katy tur, nbc news, fort worth, texas. >> reporter: this is gabe gutierrez covering marco rubio's campaign. today he was riding high until the billionaire dropped the bombshell. >> how stunning was the christie endorsement? >> stunning? no, i mean, look, guy. donald probably needs night.

christie. i respect that. >> reporter: this morning in dallas, rubio had ripped into the front-runner. >> what we are dealing with here, my friends, is a con artist. >> reporter: mocking a series of trump's misspelled tweets. >> and i only reached two conclusions. number one, that's how they spell those words at the wharton school of business where he went, or, number two, just like trump tower, he must have hired a foreign worker to do his own tweets. he called me mr. meltdown. let me tell you something. last night in the debate during one of the breaks -- two of backstage. he was having a meltdown. first he had this little makeup thing around his mustache because he had one of those sweat mustaches. then he wanted a full length mirror. maybe to make sure his pants weren't wet. >> reporter: rubio's all out of salt coming out of last night's debate in houston. he berated trump for his hiring practices.

>> if he hadn't inherited $200 million, you know where he would be >> reporter: and his slogans. >> now he's repeating himself. >> no, no, no. >> i watched him repeat himself five times four weeks ago. >> i watched you repeat yourself five times five seconds ago. >> reporter: rubio faces a steep climb. polls show the senator behind trump in all 11 states. what's crucial is rubio's home state of florida on march 15th, where one poll has him trailing by double digits. >> you're guaranteeing that you will win? what happens if you don't? >> we'll win florida. >> reporter: as rubio campaigns throughout the south tomorrow, he's expected to release his own tax returns, and he's calling on the gop front-runner to do the same. but, lester, on a day when rubio woke up owning the news cycle, he found himself trumped. >> gabe, regarding some of those allegations by rubio, coming up, we've got the inside story of how undocumented workers worked at the site of trump tower.

bring in our political director, the moderator of "meet the press," chuck todd. chuck, our new poll asked registered voters which of the following would be their reaction to trump as the nominee. 51% said scared. 24% said angry. when you look at numbers like that and you look at that back and forth we just saw a moment ago, what do you make of it? >> i have to say it feels like every time we think public discourse has deteriorated to a new low, we reach a new low. it really is stunning the back and forth today that we've seen between trump and rubio. it is unpresidential doesn't even begin to describe it. but, look, the fact of the matter is you've got to give the trump campaign credit here. this christie endorsement, timing and symbolism are big with endorsements. a lot of times they're overrated, but the timing of it was brilliant. you have to say that. it shows you this is a very sophisticated campaign that trump has. he had this in his bag of tricks ready to go when he needed it. chris christie is a card carrying member of the republican

five stages of grief going on, lester, the fifth stage is acceptance with republicans. christie is a big acceptor. >> republicans soaking up the headlines today but lest we forget, democratat and voters in south carolina primary tomorrow. what are we looking for there? >> well, it should be a big win for hillary clinton. if it's not, it shows you that there is life in sanders' campaign. sanders needs to improve with african-american voters, and if he does that, we'll know because he'll come within single digits of her. but if it's a double digit win for her, it could be foreshadowing of a long night for bernie sanders on super tuesday. >> thank you. shock and horror in another american city tonight. the scene of this country's latest mass shooting. this time, four dead including the shooter and 14 wounds after that gunman went on a rampage at multiple scenes. most of the carnage inside his place of work. miguel almaguer has new developments in the investigation. >> reporter: a

gunman's facebook page. police say cedric ford used an assault rifle to hunt and kill his victims. close to 5:00 p.m. thursday, two shootings at two intersections. two people are wounded before ford speeds away. he then arrives at work, excel industries. detectives say ford opens fire on a co-worker in this parking lot, then enters the building. >> all of a sudden, pop, pop, pop, pop. >> reporter: ford fires on everyone in sight. >> he was following people out the back, and i thought he was going to shoot me. >> reporter: 14 are wounded. three killed. 24 minutes of terror only coming to an end when a police officer storms the building, taking fire as he enters. >> the only reason he stopped shooting is because that officer stopped the shooter. >> reporter: cedric ford had a 20-year criminal history. a felon charged with burglary, grand theft, and carrying a concealed weapon. in court documents, his ex-girlfriend asking for a protective order,

alcoholic, violent, depressed. it's my belief he's in desperate need of medical and psychological help. police served that restraining order to ford at excel shortly before the shooting. dennis britton jr., shot once, thought about his three children as he was rushed to the hospital. >> i didn't want to leave them. i wasn't ready to leave yet. i didn't want to die. >> reporter: tonight, heartbreak in this small community for the dead. renee benjamin was 30. brian sadowski, 44, loved rock music. joshua higbee, 31, a young father who loved his little boy. >> he didn't deserve this. >> reporter: tonight, several people remain hospitalized, including one in critical condition. police say ford was armed with an assault rifle and a handgun. nbc news has learned those weapons were bought by an ex-girlfriend, though not the same girlfriend who filed that restraining order. lester, we are told 200 to 300 people were

had that police officer not engaged the suspect quickly, the death toll could have been so much higher. lester. >> miguel almaguer tonight, thank you. for the first time, the cdc is recommending that pregnant women not attend the summer olympics in brazil. ground zero for the zika virus, which is linked to birth defects. there are now more than 100 cases in this country, and as our rehema ellis explains, several pregnant women in the u.s. have contracted it. >> reporter: for weeks, the centers for disease control had been on the lookout for pregnant women returning to the united states from countries where zika has been linked to microcephaly. today, the cdc confirmed nine pregnant american women with zika, and is investigating another possible ten. >> we described women who developed zika after traveling, got it from a place where zika is spreading, and then are currently pregnant or delivered a child. >> reporter: two pregnancies ended in abortion. of the three babies

severe birth defect. nationwide, the number of zika cases is growing. there are now 24 states and washington, d.c. with confirmed zika virus. at least 107 cases so far, all involving people who had traveled abroad. and now doctors at seattle children's research institute in washington are sounding the alarm that the birth defect linked to zika could be even more devastating than originally feared. in brain scans comparing microcephaly cases, doctors found a baby's brain with zika was so severely damaged, it was almost gone. >> suddenly seeing something this severe and this new in such numbers is unprecedented. i've never seen the like in my career. >> reporter: tonight, health officials are warning there could be thousands of zika cases in puerto rico this summer, and the race is on to distribute mosquito protection kits there. rehema ellis, nbc news, new york. still ahead tonight, millions saw

in last night's debate of exploiting undocumented workers at the site of his trump tower. what really happened? tonight, the results of an nbc news investigation into that. also you're not just seeing things. that's a unicorn, sort of. and she led police on a wild chase that's now the stuff of legend.

one. now to that controversy that has roared back into the headlines about donald trump and one of the most famous properties that bears his name,

trump, who vows to deport all undocumented immigrants, was accused in last night's debate of using undocumented labor himself at the site of trump tower. nbc news has investigated what went on there for months now, and tonight nbc news senior investigative correspondent cynthia mcfadden reveals what we found. >> reporter: last night, marco rubio let loose on donald trump. >> you lied about the polish workers. >> yeah, yeah, yeah. >> he lied 38 years ago. i guess there's a statute of limitations on lies. >> reporter: in the 1980s, undocumented immigrants did do much of the initial work on the crown jewel of his empire in new york, trump tower. which raises the question, is donald trump a hypocrite? is it accurate to say that trump tower, the construction of it began on the backs of polish workers who were unpaid? >> oh, absolutely. it's constructed on the blood, sweat, and tears of the polish

known in the industry. >> reporter: back then, attorney wendy sloan sued donald trump, his company, and others, claiming they failed to acknowledge at least 150 undocumented polish men working off the books. donald trump testified and was asked what working off the books in the construction meant. his response, i really don't know. >> they had know protective equipment, no helmets, hard hats. >> in his testimony, ep denied he knew the workers were illegal. did it ever come to your attention that any of those polish workers were illegal aliens? >> i really still don't know that. nobody has proven to me that they were illegal aliens. >> it seems he was saying, in essence, that everybody else in town knew what was going on on his own job site, a a he didn't. >> reporter: daniel sullivan, a labor relations consultant who had been convicted of tax evasion, testified that during the demolition, trump himself knew he was using illegal workers

>> there's no question in my mind. i mean he said it to me point black. >> reporter: nbc spoke with sullivan in 1989. he has since died. >> donald's lying. flat out. he knew exactly what was happening. >> reporter: one of those workers says he was promised $5 an hour but wasn't paid for all of his work. you must have been angry? >> very angry about that. >> reporter: he was one of only a few polish workers with a green card. several undocumented workers testified at the time they were making only $4 an hour while the american union workers were making 12 to 14. they also said they were not paid for months of work. but at the time, were too afraid to protest outside the building. >> they're looking for not legal people so that people are very afraid of all that. >> reporter: mr. trump told us it was the contractor's responsibility to pay the demolition workers, not his.

agreed. still, he never reported the workers or tried to get them deported. mr. trump also told us he would have done nothing different. and, again, last night defended himself. >> i've hired tens of thousands of people over my lifetime. be quiet. let me talk. i've hired tens of thousands of people. he brings up something from 30 years ago. it worked out very well. everybody was happy. by the way, the laws were totally different. that was a whole different world. >> reporter: despite rubio's claims, what trump ultimately paid to settle the matter was sealed by the court. nonetheless, in the final ruling on yet another case involving the polish workers and trump tower, the u.s. court of appeals wrote that in the end, time generally reveals what a falsehood hopes to hide. but when it comes to mr. trump's appeal among voters, consider this. one of the polish workers who didn't get

thought donald trump might be a very good president and was considering voting for him. lester? >> cynthia mcfadden tonight, thank you. we're back in a moment with that irs hack far worse than we were first told. how you'll be able to

stolen. disturbing news from the irs today revealing that a cyberattack may have affected far more people than first reported. in all, 700,000 households may have had their information stolen. experts say we could see a surge in fraudulent tax returns. the irs says it will notify the affected taxpayers in the coming days. a hollywood passing to note tonight. tony burton, who was best known for playing apollo creed's trainer in the "rocky" movies has died. burton was a successful prize fighter of his own as a young man before moving into acting, aer paing in six "rocky" films in all.

the 88th academy awards are this sunday and it's one of the most dpev in recent history. many are betting leonardo dicaprio will take home his first best actor oscar, and brie larson is the best actress favorite for "room." but overshadowing all this controversy, some like spike lee and will smith are boycotting the ceremony over the lack of nominees of color in the acting categories. when we come back here tonight, a wild unicorn chase? the great escape that had witnesses wondering what exactly

seeing? finally tonight, whether you knew it or not, it's national tell a fairy tale day, and do we ever have the right story for the occasion. it's about a beloved pet that got loose and had something thinking maybe for a split second are unicorns real. nbc's joe fryer has our tale. >> reporter: one can only imagine what drives in rural california were thinking when this galloped into sight. >> the calls were coming in as a unicorn running around out there on the roadway. >> reporter: it

time in madera ranchos, california, where this horned creature led police on a three-hour chase. >> avenue 12. the owner is trying to corral her. >> reporter: turns out the unicorn was a phony. in real life, she's a pony. her name is juliette, and she belongs to 5-year-old tay item. >> i love my pony. >> reporter: juliette wears the horn to pose for professional pictures with children. but she made a run for the rainbow. >> she got afraid, and then she runned away. >> reporter: she dashed through orchards and darted in and out of traffic. >> she turned out to be stealthier than we would have imagined. >> reporter: a situation reminiscecommend. she was eventually wrangled by a neighbor with a horse that lured her out of hiding. >> the call came out that the unicorn was in custody. as tense as the situation was, that was the comedic relief needed at the time.

you'll yet escaped the wrath of the law. tatum was no so generous. >> she got a time-out because she was being a bad pony. >> reporter: her horn is now gone, replaced with two other horns, but at least everyone in this fairy tale lived happily ever after. joe fryer, nbc news. and that will leave us with a smile on our face on this friday night. i'm lester holt reporting from los angeles. for all of us at nbc news, thank you for watching and good night. >> it has been a trial five years in the making for cody wallace. what today's verdict was that could surprise you. plus ... >> i walked down the snack aisle of a grocery store and looked at all the labels.

>> and, this adorable puppy needs your help in getting a second chance. how you can help the puppy with a rare condition. >> we have a storm offshore. but it won't affect our changes too much. we will discuss them next. news 4 nightly starts now. >> you are watching news 4 nightly on your side in high definition. good evening, a verdict is in. >> a jury has found cody wallace not guilty of first degree murder charges however he was found guilty of child neglect. he had been arrested and charged with the death of thomas o'donnell in 2010. he has been in jail since his arrest. the victim was the son of his

afternoon and this morning before reaching the verdict. his attorney says he never should have been charged with murder in the first place. >> we believe had tabitha decided to go to the hospital, that this little boy would still be alive. >> sentencing on the child neglect charge is set for next month. wallace could get two to 20 years on that charge, but he will also get credit for time served. that is the past five years he spent many the county jail waiting for trial. in other news tonight, a shooting killed one reno teen and injured two others including an officer last night. sparks police say four men carjacked a vehicle in sparks and were later spotted at casino in silver springs. a deputy approached the car and someone inside opened fire hitting the deputy in the hand.