A United States Marine Corps aircraft crashed on a north Australian island Sunday, killing three Marines and injuring 20 during a multination training exercise, officials said.
Three had been confirmed dead on Melville Island and five of the 23 on board were flown in serious condition 80 kilometres (50 miles) to the mainland city of Darwin for hospital treatment after the Bell Boeing V-22 Osprey tiltrotor aircraft crashed around 9:30 a.m. local time, a statement from the Marines said.
Recovery efforts are ongoing, the statement said, adding the cause of the crash was under investigation.
Helicopters and fixed-wing aircraft had been deployed to return from the remote location with the rest of the injured, Northern Territory Police Commissioner Michael Murphy said.
One of the injured was undergoing surgery at the Royal Darwin Hospital, Northern Territory Chief Minister Natasha Fyles said around six hours after the crash..
Some were critically injured and were being triaged on arrival at Darwin's airport, she said.
"We acknowledge that this is a terrible incident, Fyles said. The Northern Territory government stands by to offer whatever assistance is required."
Australian Prime Minister Anthony Albanese said only Americans were injured in the crash when happened during Exercise Predators Run, which involves the militaries of the United States, Australia, Indonesia, the Philippines and East Timor.
The initial reports suggest that the incident involves just U.S. defense force personnel, Albanese said.
Our focus as a government and as the department of defense is very much on incident response and on making sure that every support and assistance is given at this difficult time, he added.
Melville is part of the Tiwi Islands, which along with Darwin are the focus of the exercise that involves 2,500 troops.
The Osprey that crashed was one of two that had flown from Darwin to Melville on Sunday, Murphy said.
Around 150 U.S. Marines are currently based in Darwin and up to 2,500 rotate through the city every year.
The U.S. military was also taking part in a multination military exercise in July when four Australia personnel were killed in an army MRH-90 Taipan helicopter crash off the northeast Australian coast.