Navy spokesman Lt. Cmdr. Phil Rosi says the crash happened aboard the USNS Arctic around 8 p.m. Thursday off the coast of Fort Story, Va., which is north of Virginia Beach.
The injured service members were evacuated by a second Army helicopter and taken to a local hospital for treatment.
Rosi says the training exercise involved the two Army helicopters and members of a Naval Special Warfare unit.
Names of the dead and injured have not been released.
The Arctic has returned to Naval Station Norfolk and the damaged helicopter remains aboard the ship.
The cause of the crash is being investigated.