The Australian Ministry of Defense said that a plane carrying members of the US military had an accident on Sunday morning during a training mission in the Northern Territory, Australia.
Sky News Australia reported that a V-22 Osprey helicopter crashed off the coast of Darwin with about 20 US Marines on board.
"Initial reports indicate that the incident involved personnel from the US Department of Defense and was not related to personnel from the Australian Defense Force," the ministry said in a statement.
Several people have reportedly been rescued after the aircraft crashed during drills near the Tiwi Islands north of Darwin, according to Australian state broadcaster ABC.