At least 20 students killed in a terror attack at Bacha Khan University in northwest pakistan. Militants attacked the school a new hours ago as classes were getting underway. A Spokesman Says four of the attackers have been killed. And the Government Troops have retaken control of all School Buildings now. An emergency worker says the operation is still ongoing. The army says its clearing the campus block by block trying to determine if any more militants are holed up at this moment. For more on whats been a deadly siege, lets bring in cnn islamabad producer. The army trying to clear the campus block by block. Whats the latest information you have on casualties at this stage . Reporter well, we know that at least 20 students have been killed. Theres been a state of emergency declared at all hospitals in the area as well as a nearby city. There are fears that the death toll is expected to rise. Were getting reports that theres still dead bodies inside the university, but as of right now the reports are still vague and not confirmed. It started in the mourning hours. Its a foggy morning. Its a large campus. We know there were 3,000 students within the campus, the winter semester has already started. And we also know that there were 600 additional guests who were inside the university for an event to commemorate a revolution who is the name sake of the university itself. And were seeing some footage for the first time just into cnn. As you speak, some of it from hospitals where those who have been injured have been taken. Some of it we can see soldiers and troops out 23450near the ca. This is a developing, fluid situation. Were still working to confirm a lot of this information. Sofia, the taliban no one has claimed responsibility yet as far as we know. But the ctaliban attack in 2015 not far from where this is happening today, that led a government to an act, 100 suspected militants were killed or arrested. Could this with a response to that because theres been an uptick in militant activity in this area in recent weeks. There has been a hike in militant activity in the past couple of days, actually. Theres an ongoing operation in the northern part of pakistan. Its an ongoing operation by the pakistani army. There have been fears of backlash. We dont know whos responsible for the attack. It could be any of the many militant organizations which operation in this region. Yes, there has been in the past year, since that attack happened, there has been weve seen a decrease in attacks because of the Pakistan Government and the strong response to that attack. But, again, theres been a hike. There have been attacks in the past three days in that region itself. So we dont really know who is responsible for it. Whats going on, and the its an ongoing situation. Yeah. Theres more information to gather. For now, at least 20 students we know have been killed in this horrific attack. Sofia, part of our cnn team, will continue to give updates in the hours ahead. Voting in the u. S. President ial primary begins in less than two weeks from now in iowa. And donald trump is deadlocked with his republican rival, ted cruz. But trump may have gotten an important boost by getting an endorsement from sarah palin. She praised trump for raising difficult issue and challenge the status quo. Only one candidates record of success proves he is the master of the art of the deal. He is beholden to no one but we the people. How refreshing . Hes perfectly positioned to let you make America Great again. Are you ready for that, iowa . [ applause ] no more tiptoeing around. Our troops deserve the best. You deserve the best. He is from the private sector, not a politician. Can i get a alleluia . Joining me now is cnn political commentator and the washington commentator for the new yorker. The big use was sarah palin endorsing donald trump. What shock waves has this september through the republican party, and whats the likely impact of this endorsement . Well, look, donald trump has already been striking fear in the hearts of many republicans. I mean, you can find there is now a Cottage Industry in washington of serve thetives and republican oriented columnists who are declaring they will not vote for donald trump if hes the nominee in a party. I think if there were one other figure in the republican affi affirmament who scares people in washington and elsewhere, its sarah palin. In a sense, hes doubling down on what a lot of republicans feared about trump in the first place. Yeah. Interesting. And then, of course, in 2012, sarah palin endorsed ted cruz. Now shes turned her back on him. And iowas governor is telling people not to vote for cruz. Lets listen to what he did. I believe it would be a big mistake for iowa to support him. I know hes ahead in the polls, but the only poll that counts is the one they take on caucus night. I think it could change between now and then. I think this event is an important, significant step to helping educate the voters in this state and this state is where it all begins. Not a great day for cruz. What impact is all this likely to have on his president ial bid . Well, the governor in iowa is popular with republicans. Hes the longest serving governor in america right now. Frankly, i think what we said today has a bigger impact than sarah palins endorsement of trump. Even among republicans, palin can be polarizing. I think what the governor is trying to do is send the message that as bad as trump is, a cruz strump battle that goes on far long time might be worse for the republican parties. In other words, one of these guys wouldnt leave iowa and go into New Hampshire and the rest of the states. That would be even worse for republicans. If donald trump is going to be someone thats going to be in the race for a long time, so be it. But if they can get cruz out early, thats what the republican establishment wants right now. And the other thing, just at a simple level, it shows you that ted cruz, even though hes been in politics a long time, just does not have any friends, at least in the class of elected officials both in washington and out in the states. It doesnt look that way, and on the other side of politics, Bernie Sanders is enjoying a big surge right now. A new poll has him beating Hillary Clinton by 27 points in New Hampshire. What impact is that likely to have . And just how worried do you think the clinton camp is right now . If theyre not worried, they should be. They should be terrified. Right now they are Hillary Clinton is in the position where shes likely to lose iowa and New Hampshire, and a lot of smart democrats have been saying for months even if she loses these first two states, well, the contests after that in the south and elsewhere have much different electorates. Theyre not as lily whites as iowa and New Hampshire, and African American and latino voters are very strongly backing clintons candidacy. Thats what theyve been telling themselves for a long time. But if you get into a situation where she loses both the early states, all bets are off and who knows how far the sanders candidacy should go. They have to start hitting sanders hard and do it now. Pretty shaky on both sides of the political aisle here. Ryan, many thanks. Always a pleasure to speak with you. My pleasure. Zblnc we are hearing from some of the americans released by iran. Theyre expressing gratitude. One of the diplomats explains the process of getting them out. Jason rezaian in the first video since his release. Still, the first of the freed americans to speak says the detention ended only after one final night of fear and uncertainty. Up until the last weekend, we were all worried and concerned. We were put in a small room without access to any information. We kept being told were going to be taking off in two hours until it became six and ten. So a total of almost two and a half days was really nerve wracking. The american diplomat who negotiated the release over 14 months of secret talks told us the first sign of trouble that evening was when they could not locate rezaians wife and mother. I was very concerned. We stopped the whole thing. Reporter it turns out they were being held on their own without any communication in a part of tehrans airport controlled by the military. I said no. The entire thing is off unless theyre on the airplane. Reporter you would have killed the deal if his wife and mother werent on the plane . The it was part of the deal. Period. Reporter and do you think the iranians at this point for trying to change the terms . What were they trying to do . Its unclear. Theres a lot of people in the iranian system. And the people who hold the keys to the prison cells. That never wanted this to happen. Reporter he was not convinced the deal was back on until a representative in iran narrated the scene second by second by the telephone. He was on the tarmac and described a van approaching the airplane. The doors opened and one by one he explained that was jasons wife, his mother, jason, amir, and saeed. That was the trigger for us. Ill never forget his voice in my ear. Reporter he says the talks almost fell apart several times including this moment in october when he showed up unexpectedly at Nuclear Talks with iran in vienna. But again, hope disappears. We made a lot of progress there, but then when i got back together with my counterparts, they went back to square one. Reporter ive spoken to diplomats involved who describe the urgency of the cases including fears that Jason Rezaian faced the prosect of not just a long prison sentence, but also the possibility of a death sentence. Jim sciutto, cnn, washington. Were going to take a short break here. Still to come, Amnesty International says Kurdish Forces who are fighting isis are also the destroying entire villages. And displacing thousands of arabs and the group says that it might amount to war crimes. The 88th southern parallel. We had traveled for over 850 miles. My men driven nearly mad from starvation and frostbite. Today we make history. Bienvenidos welcome to the south pole if youre dora the explorer, you explore. Its what you do. What took you so long . If you want to save fifteen percent or more on car insurance, you switch to geico. Its what you do. You did it, yay we are still following breaking news out of northwest pakistan. A siege at a university thats left at least stude20 students. It began at Bacha Khan University as classes were getting underway. Four attackers have been killed. An emergency worker says the operation is still ongoing. We are told there are still bodies inside some of those buildings, and officials believe the death toll could rise. So far no one has claimed responsibility for this attack. We want to turn to a top story now in the United States. Michigan governor says hes sorry about the crisis in flint where Drinking Water is contaminated with lead, and he is promising to fix it. Snyder is asking lastate law clerks for money to help address the crisis. He says hell release his emails about the water supply to provide accountability. Government failed you. Federal, state and local leaders, by breaking the trust you placed in us. Im sorry most of all that i let you down. You deserve better. You deserve accountability. You deserve to know that the buck stops here with me. Most of all, you deserve to know the truth, and i have a responsibility to tell the truth. The truth about what weve done and what well do to overcome this challenge. There is so much outrage over this. A crowd of protesters gathered outside the michigan capital on tuesday. Theyre calling for snyders resignation. Some want him arrested. Meanwhile the u. S. President met with flints mayor pledging his support. The mayor has been helping to distribute bottled water to residents. Three, two, one. By way of background. The crisis started in 2014 when the city switched its water supply to the flint river. An estimated 500 people claim they are suffering from Health Issues and researchers say the effects on children and the unborn could last for many years to come. Joining me now to talk about rick snyder and the water crisis in flint is someone from the american civil liberty unions of michigan. He broke this story wide open. Thank you for joining us today. You are, in fact, the only investigative journalist on staff at aclu nationwide. First, why is flint, michigan an important place to investigate for the paper . I was hired to look at a law that allows the governor to appoint socalled Emergency Managers who are given complete control over the operations of cities, school districts, counties, that are deemed by the state to be in financial distress, taking away the power from dually elected local officials and putting it into the hands of one person thats accountable only to the governor. And this is a place that is economically distressed . Youve talked to so many people getting their stories on what theyve experienced with this literally brown, unsafe, toxic water. The tell me some of the most shocking things you found. Well, the biggest thing that is effecting the most is what happens to children when theyre exposed to elevated levels of led. Which, they have been exposed to it since april of 2014 when the state in a move to save money switched flint from the detroit system that had been providing clean, safe water for 50 years and started using the very polluted, highly corrosive flint river for the towns Drinking Water. You helped gather hundreds of samples. You were pushing officials for answers. They were dodging the issue. You also exposed a memo last year which acknowledged that something was, in fact wrong. Let me read you a statement the epa released a short time ago. Quote, the situation in flint of a large system switching from purchasing treated water to untreated water, is highly unusual. Epas ability to oversee the Quality Management was impacted by failures and resistance at the state and local levels to work with us in a proactive manner consistent with the seriousness of the risks to public health. We must ensure the situation never happens again. What was the reason behind this government psychiatryscrew up . Was it really just to save 100 a day . It goes back to the emergency manager law i referenced. Because it was the state with the emergency manager in charge that made the decision to begin making the river in the first place. Because that was a disastrous decision, and then one that was charged with overseeing the city and making sure they conducted lead tests properly, there were no independent check and balances. All strings lead back to the governor. It was his people that were doing this. It was his people that were covering it up for the mistakes made by other of the governors people. It gets to the heart of this problem with this law. It takes away the kind of democracy that most americans take for granted, eliminates necessary checks and balances and consolidates power in one place. In this case, its the Governors Office. And Governor Rick Snyder addressed the state on tuesday. Im just wondering how much resistance and skepticism youre facing. The past year has been an uphill battle and the governor hasnt necessarily acknowledged auld youd wish he did. Correct. And as a matter of fact, every step along the way the tactics were to deny there was a problem and attack the people who were trying to bring the truth to light. They attacked someone from the epa when he leaked the memo that really exposed all of this. They attacked and tries to discredit a professor of Virginia Tech who is a recipient of a genius grant and a hero in washington d. C. Where he hennlp expose the lead in their water, and he attacked a pediatrician at a Medical Center who after we conducted our own tests in con ju junction with her and found unacceptably high levels of lead in the water, she did her own tests to determine that the levels of lead in the blood of flint children doubled after this switch to the river. The Governors Office tried to attack her credibility and integrity as well. All let me jump in and ask you this. You do have Hillary Clinton running for the democratic nomination for president mentioning this issue during the most recent debate. There is some momentum behind this issue. Where do you go from here . Well, theres two things. Number one is to do everything humanly possible to make sure that the people of flint once again get clean, safe Drinking Water. The other thing is to determine who is responsible for this disaster, who is responsible for the poisoning of these children, and bring them to justice. Its something that we will continue to follow closely and thanks to you for bringing a spotlight on this issue. Investigative reporter with the aclu. Thank you for your time. Thank you. Well take a short break. We will have more on our breaking news story, the siege at a university in northwest pakistan that has left at least 20 students dead. A live report when we come back. Welcome back to our viewers here in the United States and all around the world. We are following breaking news. Im errol barnett. Lets update you on the developing story out of pakistan. At least 20 students are dead in the northwest part of the country after militants stormed Bacha Khan University just has classes were getting underway. Security forces say theyve killed at least 40 of tfour of attackers. A local official says its still ongoing, and he expects the death toll to rise. We want to go live to alexandra field. We know at least 20 students have been killed in this deadly attack. We understand this is still an ongoing operation. What details do you have on this attack . Reporter its too soon to have any of the authorities getting their hands around the full extent of the situation. There are concerns there could be more two have been killed today. What we know at this point is some of the