The crash of the CH-46 Sea Knight helicopter killed 12 U.S. and 4 British soldiers, officials said.
U.S. military officials said they did not have further details about the crash.
Military officials said they did not know if the helicopter had been hit by hostile fire or crashed for some other reason.
The Marines use the Sea Knight, a bus-like helicopter with two large rotors, to fly troops from ships at sea or base camps to forward positions.
The Navy and Marines grounded all 291 Sea Knight helicopters in August after an inspection of one helicopter in North Carolina found a crack in a rotor assembly. A Marine Corps CH-46 crashed in 2001, killing three Marines and injuring two.