Members of the 628th Security Forces Squadron respond to an aggressor during a mock hostile situation during the active shooter training exercise on Joint Base Charleston, S.C., Sept. 22, 2010. The AST exercise prepares first responders on how to react to a hostile situation. (U.S. Air Force photo by James M. Bowman/released)

Members of the 628th Security Forces Squadron go up a stairwell to find an aggressor during a mock hostile situation during the active shooter training exercise on Joint Base Charleston, S.C., Sept. 22, 2010. The AST exercise prepares first responders on how to react to a hostile situation. (U.S. Air Force photo by James M. Bowman/released)

Officer John Kimbler subdues an aggressor during a mock hostile situation during the active shooter training exercise on Joint Base Charleston, S.C., Sept. 22, 2010. The AST exercise was a joint operation between both Air Force and Navy personnel and tested the deployment of rapid intervention techniques. Mr. Kimbler is a security forces officer with the 628th Security Forces Squadron. (U.S. Air Force photo by James M. Bowman/released)

Members of the 628th Security Forces Squadron move through the hallway looking for an aggressor during a mock hostile situation during the active shooter training exercise on Joint Base Charleston, S.C., Sept. 22, 2010. The AST exercise was a joint operation between both Air Force and Navy personnel and tested the deployment of rapid intervention techniques. (U.S. Air Force photo by James M. Bowman/released)