Eleven troops are presumed dead in Florida after an Army helicopter crashed Tuesday, a military official announced. Search and rescue efforts had been underway at a remote beach between Pensacola and Destin after a chopper was reported missing last night. Seven Marines and four members of the crew were on board. The Marines are from a Camp Lejeune Special Operations group and the aircrew are from the National Guard; their names have not been released. Debris was found at around 2 a.m. The helicopter was being used during a training exercise, and a second chopper taking part returned to the base safely.