Investigators have been trying to determine what motivated a gunman who opened fire in a classroom building on Friday at the Naval Air Station Pensacola. He used a handgun and was killed after two deputies exchanged gunfire with him. The shooter was identified by the FBI as Mohammed Alshamrani -- a 21-year-old second lieutenant in the Saudi Arabian air force. He was a student naval flight officer, according to an FBI spokesperson. The shooter does not appear to have ties to terrorist groups, two sources told CNN. Escambia County Sheriff David Morgan told CNN's Erin Burnett that the FBI had...