Three US Marines were killed when their Osprey, a hybrid vertical takeoff aircraft, crashed on a remote tropical island off the northern Australian mainland on Sunday, a navy official said.
"There were a total of 23 people on board. Three died and another five, injured and in serious condition, were taken to the Royal Darwin Hospital," the official said in a statement.
The other wounded are treated at the scene, the same source said.
The ship was participating in joint exercises between the United States and Australia.
Rescue operations were complicated by the crash site, the remote and sparsely populated Melville Island, located some 60 kilometers north of the Australian mainland.
"Rescue operations continue," the US authorities said, adding that an investigation was underway to determine the causes of the accident.
Prime Minister Anthony Albanese called the incident "tragic" and "regrettable".
The machine was participating in the Predators Run exercises, a series of military exercises organized jointly by the US and Australian armies.
In recent years, the US military presence in northern Australia has increased as both powers seek to thwart China's growing influence in the Asia Pacific region.
The Osprey aircraft, the fruit of a US cooperation between aircraft manufacturer Boeing and helicopter specialist Bell, has two wingtip motors, which rotate to switch to helicopter mode for takeoff or airplane mode for faster flight.
His safety was put into question after several fatal accidents.
Last year, four US Marines were killed in Norway when their V-22B Osprey crashed during NATO training exercises.
In 2017, a US Army Osprey crashed into the sea after striking the stern of a ship as part of a US-Australian military exercise, killing three people.
In April 2000, 19 Marines were killed when an Osprey crashed while training in Arizona.
Earlier this year, the US military temporarily suspended all pilots not flying critical missions, forcing them to undergo additional training after a series of security incidents.
Military exercises in Australia have already left four Australians dead last month, when a Tajan helicopter crashed into the sea as part of the "Talisman Sabre" maneuvers, which brought together 30,000 soldiers from Australia, the United States and several other world powers. region. .
Crashed near the Whitsunday Islands while taking part in a night operation.