WASHINGTON — A senior U.S. defense official says all six reported killed in the crash of a U.S. helicopter in Afghanistan were U.S. Marines.

The helicopter crashed Thursday in Afghanistan’s southern province of Helmand.

The defense official who said all six were Marines spoke on condition of anonymity because the U.S. command in Afghanistan had not yet publicly released details, including the nationalities of the dead.

The official says there is no indication that the helicopter was hit by enemy fire.