what happened to make sure that everybody is secure. and i want to just assure all of us that we are going to get to the bottom of exactly what happened. >> this is the second such incident in ft. hood since 2009. for the second time within five years, this is the chilling way so many people on post learn that something once again was terribly wrong. >> seek shelter immediately. >> that's what residents heard on the base. this is what one eyewitness saw. >> they are actually escorting a group of soldiers out of a building now at gunpoint. everyone is coming out with their hands in the air, required to drop down to their knees. >> and a group of soldiers like five, ten? >> no, mass soldiers.