(CBS News) - Below is a rush transcript of "Face the Nation" on March 11, 2012, hosted by CBS News chief Washington correspondent Bob Schieffer. Guests are former House Speaker Newt Gingrich and President Obama senior campaign adviser Robert Gibbs. A roundtable with CBS News correspondents Norah O'Donnell and David Martin also joined the program
BOB SCHIEFFER: Today on FACE THE NATION, the Republican campaign goes South, and a terrible turn in the Afghanistan war. As tensions grow in Afghanistan in the wake of a Koran burnings, an American soldier apparently opened fire for no legitimate reason on Afghan civilians. We'll have the latest from Mandy Clark in Kabul.
Back home, the Republican campaign grinds on. Rick Santorum swept the Kansas caucuses, and Mitt Romney won in Wyoming, but there was no mistaking that the big battles were down South.
MITT ROMNEY: Good morning, y'all. Good to be with you. I got started right this morning with a biscuit and some cheesy grits. I'll tell ya. Delicious.
NEWT GINGRICH (Republican Presidential Candidate/Former House Speaker): It was the first time he'd ever tasted grits.
NEWT GINGRICH: I just wanted to reassure all of you that I have had some acquaintance in a variety of forms with-- with shrimp, with cheese, with gravy. I get it.
BOB SCHIEFFER: It was one of those you can't make it up weeks on the campaign trail. So where do things stand now? After winning Georgia, Newt Gingrich is still dancing, but can he or Santorum stop Romney? We'll ask him. Then, we'll talk to a top Obama campaign advisor Robert Gibbs. The latest on the campaign and Afghanistan with analysis from correspondents, Norah O'Donnell and David Martin.
This is FACE THE NATION.
ANNOUNCER: From CBS News in Washington FACE THE NATION with Bob Schieffer.
BOB SCHIEFFER: And good morning again. The overnight news from Afghanistan is sober. At least fifteen Afghans by some counts are dead, and more are wounded after an American soldier went on a shooting spree. It happened in Kandahar province just at a short distance from a U.S. Military base where villagers stood in silent shock this morning when officials collected bodies and tried to sort out what had happened. CBS News correspondent Mandy Clark is in Kabul this morning. Mandy, what have you been able to find out?
MANDY CLARK: Well, we understand the American soldier left his remote base in Kandahar province this morning around dawn. And he went house to house shooting villagers. According to an Afghan official, in one home, he killed eleven civilians including women and children. He has been detained and an investigation is ongoing.
BOB SCHIEFFER: Do we have any idea what prompted this?
MANDY CLARK: No. American officials have been asked what caused the attack to happen. There is no indication of what the motivation could be. And they haven't made any link to the victims and the soldiers, so it's very unclear why he went on this shooting rampage.
BOB SCHIEFFER: All right, Mandy Clark in Kabul. Mandy, thank you so much. Security correspondent David Martin is with us in the studio. David, can you add anything here?
DAVID MARTIN (CBS News National Security Correspondent): Well, as she said, the soldier is in custody so sooner or later presumably they will find out his motive. But the motive seems almost beside the point. The number one mission for U.S. troops in Afghanistan is to protect Afghan civilians and for an American soldier just to open fire on Afghan civilians just undercuts the mission of U.S. troops in Afghanistan.
BOB SCHIEFFER: David, thank you. You'll be back later and we'll be joined by our White House correspondent Norah O'Donnell who will have more on all this. But let's turn now to the campaign, and Newt Gingrich who is with us this morning in Birmingham. Mister Speaker, good morning. What would you do this--
NEWT GINGRICH (Republican Presidential Candidate/Former House Speaker): Good morning.
BOB SCHIEFFER: --morning if you were President?
NEWT GINGRICH: Well, I think you have to reassure the Afghan people that there will be transparency, that justice will be done. We're the opposite from al Qaeda and the Taliban. They kill civilians deliberately. We protect civilians and when a tragedy like this occurs, we have an absolute obligation to deal with it out in the open and to do so to ensure that justice is done and that they know how serious we are about protecting the innocent of-- of every background and every nationality.
BOB SCHIEFFER: You were pretty strong about the President's apology over the burning of the Koran. Well, what-- what can he say now? What should he say now?