welcome to a special edition of "world news tonight." the race for iowa now two days away. the final push, candidates furiously crisscrossing the state already. donald trump stepping off his plane and stepping up his attacks. >> ted cruz, who was not born on u.s. soil, it's a problem. how the hell can he run for president? hillary clinton making her case to last-minute voters. tonight, new questions about those top-secret e-mails once again following her campaign. our team right here on the ground. and breaking news. captured. three dangerous fugitives back behind bars. police catching the remaining two after more than a week on the run. also breaking, the deadly shooting. chaos erupting at a packed event. police rushing to the scene. and the zika virus on the rise. 36 cases discovered in a dozen states.

dr. rich besser with the military going door to door in heart of the outbreak. and, bringing down the house. the dream home on the hill, and the nightmare discovery forcing them to tear it down. >> from abc news, this is a special edition of ""world news tonight."" reporting from iowa, cecilia vega. good evening. thank you for joining us on this saturday. as we come on the air tonight, the state capitol right here behind me and the countdown to the iowa caucus is on. you can feel the energy all across this state and the candidates are everywhere. take a look at this map the presidential hopefuls making 57 different campaign stops today alone. on the republican side, so much fire. donald trump jetting in on his personal plane today, ted cruz on track to visit every county in the state. and now, marco rubio with the momentum. our team is right here covering it all and abc's tom llamas starts us off.

>> reporter: donald trump and his private jet making a flash landing into iowa. the crowd waiting not his largest, but ready for their caucus marching orders. >> this is now crunch time. this is it. this is what it's all about. so we have to get out there and caucus, and do all of the things that we have to do, or we've all wasted our time, folks. >> reporter: trump also making his push on social media, reminding evangelical voters he owns a bible and loves it. >> and it's just very special to me. and, again, i want to thank the evangelicals. i will never let you down. >> reporter: and ivanka trump a born and bred new yorkers now out with an infomercial for iowans. >> hi, iowa, i'm ivanka trump did and i am really excited to tell you how to caucus for my father. it's a secret ballot. you just write down the name "trump," and you are done. and that's it. >> reporter: trump also not letting up on his birther attack against the canadian-born senator ted cruz. >> now they're saying he just

can't run, you just can't run. >> reporter: cruz trying to laugh off those attacks. >> i will say this, when donald insults you, it's always interesting. >> reporter: but to donors cruz admitting trump is getting to him. cruz writing in a fund-raising letter today, "the latest polling shows that donald's attacks are swaying voters." with just two days left, cruz going hardest not on trump but on senator marco rubio. >> when he got to washington, he made the decision to lead the fight to pass amnesty -- >> reporter: rubio telling voters cruz may lose in iowa and is now in panic mode. >> he had decided to run a very deceitful campaign on the end on some things. people see through that. >> reporter: in a rare move, the rubio campaign is launching a 30-minute tv special profiling rubio in iowa's largest tv market is. this is a similar move to what president barack obama did in his first run for the presidency during the general election. tonight, donald trump rallies here in davenport with jerry

falwell jr. he hopes will help him with evangelical voters. cecilia? >> and you'll be covering it all, tom llamas, thank you. for democrats in this final sprint the two front-runners today seeming to table the gloves off. hillary clinton's campaign turning into a family affair with husband bill and today, daughter chelsea right there. bernie sanders speaking to packed halls. tonight, the big question, what is clinton saying about those e-mails on her private server, now deemed top secret? abc's jonathan karl has this side of the story. >> reporter: hillary clinton campaigned today in ames, iowa, with some of her most high-profile supporters. daughter chelsea and gabby gifford. >> speaking is hard for me. but january -- come january i want to say these two words. madam president. >> mrs. clinton needs all the help she can get as she faces a tougher than expected race in iowa. as she rallied the crowd no

mention of the story hanging over her campaign. the state department now says there was top-secret information in 22 of the e-mails sent from her private account as secretary of state. >> madam secretary, why was there top-secret information on your e-mail? madam secretary? >> reporter: earlier, mrs. clinton told cnn nothing had changed. >> i didn't send or receive any e-mails marked classified. >> reporter: bernie sanders had nothing to say about the e-mail issue as he made his final push. praising iowa democrats for what they did eight years ago when barack obama scored an upset win over hillary clinton here in iowa. >> thank you, iowa, for leading the country in that direction. >> reporter: when we caught up with sanders, he echoed obama's 2008 slogan "yes, we can." >> i think one of the problems we've had, jonathan, the people said, i like bernie and i like his ideas but he can't win. >> so can you? >> yeah, we can. many of the polls out there suggest we can beat people like donald trump and beat them

pretty badly. >> reporter: we're at the point basically every campaign event is packed. here in ames for hillary clinton, they're down on the floor, they're up here in i guess the upper deck cheap seats. basically anywhere they can go and still get a glimpse of the candidates. the final weekend means crunch time for the volunteers. you're running out of stickers. >> we'll never run out of stickers, we'll have stickers till the cows come home. and we have a lot of cows in iowa. >> and jon joins us now here in iowa, jon, polls show one of clinton's biggest challenges is trust. what are voters out there telling you about this latest e-mail controversy, will it hurt her? >> i'm not hearing democrats concerned about this, not clinton supporters, not sanders supporters. they're aware of it, they know republicans are attacking hillary clinton for it. it may marginally cut into her central argument here, and that is she is the candidate most likely to win in november. >> not what she wants to be talking about two days out. jon, thank you. the race is tight on both

sides and turnout at the caucuses will make all the difference. sure what the candidates say at every rally counts the most, bunt so does their operation to get out the sote. abc's david wright with the last-minute ground game. >> reporter: crunch time here in iowa, so the volunteers are pounding the pavement. knocking on doors. leaving calling cards and sometimes striking out. >> are you guys going to caucus on monday? >> no, we won't be here. >> reporter: this husband and wife came here from dallas to help out. what is it that would make you come all this way for that? >> it's time that we kind of fit our time and our bodies where our mouth is. >> reporter: people are coming from far and wide. that's how strongly they feel. have you ever done this before? >> no. >> reporter: where did you come from? >> phoenix. >> reporter: you drove from phoenix? >> starting yesterday morning. >> reporter: they said the democrats they're meeting seem pretty happy with their choices. >> kind of voting for bernie,

but if it comes down the other way, i'll vote for the other one. >> reporter: republicans are passionate too. some of them nervous. today at trump's rally in dubuc -- >> do you see him as serious candidate? >> i'm afraid he might be. >> reporter: there were a lot of trump voters, also a few trump tourists. >> to be honest i'm here to be entertained. i don't take it seriously. >> interesting, you wanted to be here for the show? >> yes are. >> reporter: the crowd in cedar rapids getting ready for a bernie sanders rally about to start. state officials tell us they're preparing for an absolute avalanche of caucusgoers, but incredibly there are some out there who haven't made up their minds. the great undecided. this week a show including donald trump, bernie sanders, and hillary clinton. also david muir joins us in iowa tomorrow for another special edition of "world news tonight." now to our other top story, breaking news from california.

two more escaped prisoners caught. all three back behind bars thanks to a lucky tip in san francisco that led to this stolen van. one inmate caught after a chase, the other caught hiding inside. also in that van, ammunition. abc's matt gutman with how this capture went down. >> reporter: tonight, that chaotic chase in downtown san francisco. a bystander spotting that white gmc van. >> officers approached the van, as hossein nayeri fled the area on foot. >> reporter: police in pursuit. it's hussein nyyeri, wanted for torture and kidnapping. >> he's running eastbound up towards stanyan now. >> reporter: then -- >> code 4, we've got him down. >> reporter: but murder suspect jonathan tieu is still in the van. >> that van right to the your 5:00, can you stand by? there might be another person in there. stand by, take a look in that van. >> reporter: he's arrested without incident. found in the van, at least a dozen rounds of ammunition.

but no gun. the three escapees busted out of the orange county jail last saturday, hacking through bars and pipes and rappelling down the jail facade. nayeri had apparently enlisted the help of a jail english teacher with whom he'd exchanged loving letters. >> we do know it was much closer, much more personal than it should have been. >> reporter: shortly after the jail break saturday, bac duong steals that van spotted today. on friday he surrendered, casually allowing cops to cuff him, nodding to them as they escort him right back to the jail he fled. investigators are searching for a possible gun to go along with the ammunition they found and for possible come missions. get this, cecilia, after all of this those two felons caught today face only an additional three years in prison for that jail break. >> matt, thank you. another breaking story tonight, gun fire at a conference center in denver. at least one person dead, several others injured. the violence breaking out at a motorcycle expo.

abc's ron claiborne on what we know at this hour. >> reporter: it happened just before 1:00 this afternoon. at a gathering of motorcyclists. >> shots fired at the coliseum at the motorcycle rally. >> reporter: early details were sketchy but it appeared someone fired shots and stabbed a number of people in what police are calling a disturbance at the colorado motorcycle expo. the show attracts a large number of bikers. >> we have one deceased party and multiple victims that were taken to the hospital. >> reporter: officials said at least seven people were being treated at denver health medical center, which at one point was placed on lockdown. and an extremely heavy police presence outside. >> this is an active, ongoing investigation -- >> reporter: police say they were questioning one person, but at this hour no one has been arrested. and what triggered this outbreak of violence still under investigation tonight. ron claiborne, abc news, new york. next, inside the desperate battle against the zika virus. here at home reports of 36 people contracting the disease

in a dozen states, four of them pregnant women. but tonight the urgent fight to stop the epidemic at its source and that is where we find abc's chief leltsd and medical editor dr. richard besser. >> reporter: door to door, here in brazil they're desperate to block the explosive growth of zika. there's no vaccine, no treatment. all we know is mosquitos carrying it. soldiers are scouring neighborhoods. there's a government requirement that every house in this area is visited at least once a month by the soldiers to look for any place a mosquito could breed. they're meticulous. he's even looking to see where the water drains out of the refrigerator, the condensation. that's all it would take for mosquitos to breed. in these sprawling shanty towns, residents store fresh water in large tanks, often with mosquito larvae like this. soldiers sanitize each tank to kill the eggs. in this clinic we see firsthand why the stakes are so high. >> this is scary. we're dealing with a disease that we have no information about.

>> reporter: these babies have microcephaly, abnormally small heads and brains. there are hundreds of cases here. more than 4,000 in brazil. scientists suspect they're directly connected to a zika virus infection during pregnancy. but we don't know how. health officials are bracing for more. while moirds here struggle to plan an uncertain future for their babies. until zika virus is under control in brazil and the other countries the cdc says it's far too dangerous for pregnant women to travel to those areas. they should stay home. cecilia? >> a good warning, dr. besser, thank you. to another health emergency now. major developments from flint, michigan, families there being told even filtering their water will not make it safe to drink. the lead levels way too high. tonight, a bombshell e-mail after the water troubles there began, city officials were given bottled water, but what about all those families? here's abc's alex perez.

>> reporter: embattled michigan governor rick snyder is facing harsh criticism tonight for the latest revelation in flint's ongoing water crisis. e-mails exbody posed by progress michigan reveal the state shipped bottled water to its workers in flint over eight months before the residents were officially told the drinking water was unsafe. governor snyder's reply. >> i had no knowledge of that taking place. >> reporter: the e-mails included a department memo, which said coolers will be provided as an option. quote, "as long as the public water does not meet treatment requirements." the city had warned sick and elderly residents of potentially harmful chemicals in the water. but reassured them it was otherwise safe to drink. the state defends their decision, saying they only provided bottled water to employees temporarily until that particular chemical threat was over. dangerous levels of lead were later found in flint water, and about 200 kids so far have tested positive. >> knowing that somebody did this to my kid? it's hard.

i can't say sleep at night. >> reporter: and tonight, officials are now warning that the filters they handed out to residents may not be effective enough to keep their water safe. alex perez, abc news, flint, michigan. there's still much more ahead on this special edition of "world news tonight". the dream home suddenly a nightmare. the dangerous discovery that brought down this house. and facebook is stepping into a hot debate, a new ban going into effect for all of its users.

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>> it's one of those devastating kind of pieces of news. >> reporter: ronald martell hadn't even moved into his san francisco home, when he discovered it sliding downhill, threatening the neighborhood below. his only choice, tear it down. it's not just this home that was in danger. five others were also on this slippery slope. and now those homeowners are worried they could be next. >> you wake up one morning and the comment is, you may have to lose your home. that's pretty scary. >> reporter: tonight demolition is almost done. still, no one knows what triggered the slide. but already, martell is hopeful he'll be able to rebuild. >> for californians we rebuild and move on. >> reporter: no other homes are being torn down just yet. but homeowners nearby are required to hire an engineering firm to prove their houses are not at risk or face the wrecking ball as well. cecilia? >> aditi, thank you. still ahead on "world news

tonight" -- facebook smack in the middle of one of the most contentious issues in america. tonight what users can no longer do. and it's beyonce like we have never seen her before. but why is this new video sparking so much outrage? i'm here to get the lady of the house back on her feet. and give her the strength and energy to stay healthy. who's with me?! yay! the complete balanced nutrition of great tasting ensure. with 9 grams of protein and 26 vitamins and minerals. ensure. take life in!

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and visit farxiga.com to learn how you can get it for free. finally tonight, the first votes in the 2016 race to the white house now just hours away. iowa, where cows outnumber people, now the center of the political world. tonight, the one thing everyone wants to know but is afraid to ask. the hawkeye state. >> what's it like to be greeted by bacon? >> amazing. >> reporter: where politicians come to flip pork chops -- pose with a cow made of butter. take kids for a spin in their chopper. did we mention the pork chops? so. many. pork chops. >> pork chop on a stick. >> reporter: it's enough to make a politician scream. >> yeow! >> reporter: but it all comes to a head at those caucuses. we came to drake university. hi, you're the caucus expert? to ask that burning question. what the heck is a caucus? it's complicated, so they gave us a demonstration.

for the democrats, groups of iowans gather to choose delegates who then go on to choose their party nominee. one side tries to convince the other to join their team. or a break tie with food. or -- >> rock paper scissors. that's one possibility. >> really? >> reporter: the republicans have it a lot airs. they write down a candidate's name on a slip of paper, and done. if it sounds like a bunch of song and distance -- dance well, there is a caucus musical. ♪ ♪ iowa >> reporter: but just remember, iowa launched presidential runs for jimmy carter, two george bushes and barack obama. and come monday, they may just launch the next leader of the free world. just two days away. "gma" and "this week" in the morning, david muir anchors right here tomorrow night. i'm cecilia vega. good night.

nin who sees something, say something. >> on abc 7 news at 5, the police credit an observing woman catching two jailless jail escapeees. another hunt underway in the south bay, extreme measures by burglary suspects, and why this is a familiar scene at super bowl city. live from the kgo broadcast center, this is abc 7 news. eight days on the run came to an end day in san francisco for a pair of violent criminals who escaped from a jail in orange county. hello, i'm eric thomas. we begin with developing news. the hunt for two prison escapees ends here. police today in san francisco arrested these two men after a tip from a woman who