Washington: Seven Marines and four army soldiers aboard a helicopter that crashed off the coast of Florida are presumed dead, US military officials said on Wednesday.
The Black Hawk helicopter went missing on Tuesday night during a routine training exercise.
Search teams found debris in the Gulf of Mexico about six hours later and determined that the aircraft crashed near Eglin Air Force Base, about 80 km east of Pensacola.
Some human remains have been discovered near the crash site, Eglin base spokesperson Andy Bourland told NBC television, adding that parts of the helicopter washed up on land.
Fog in the area, which may have played a role in the accident, was hampering efforts to recover the bodies, authorities said.
The seven Marines were from a special operations unit based at Camp Lejeune, North Carolina. The helicopter and its four-people crew belonged to the Louisiana Army National Guard.
The other UH-60 Black Hawk taking part in the exercise landed safely.
Bourland said it was too early to make any definitive statements about the cause of the crash.