Base officials said the Marines were part of a Camp Lejeune, North Carolina-based special operations group. The soldiers were from a Hammond, Louisiana-based National Guard unit. Names of those involved were not immediately released, pending notification of next of kin, Bourland said. Bourland said the Army helicopter took off from a nearby airport in Destin and joined other aircraft in the training exercise. The training area includes 20 miles of pristine beachfront that has been under the control of the military since before World War II. Military police keep a close watch on the area and have been known to run off private vendors who rent jet skis or paddle boards without permission. Test range manager Glenn Barndollar told The AP in August that the beach provides an ideal training area for special operations units from all branches of the military to practice over the water, on the beach and in the bay. The military sometimes drops trainees over the water using boats or helicopters and the trainees must make their way onshore.