The incident took place north of Darwin as some 2,500 troops from five countries began joint military exercises.
A United States military aircraft has crashed off the coast of northern Australia, killing three Marines and injuring 20 during a multination training exercise, officials said.
Three Marines were confirmed dead in the incident on Sunday, after the Bell Boeing V-22 Osprey aircraft crashed at about 9:30am local time (01:30 GMT), the US Marines said.
There were 23 people on board the aircraft at the time of the crash near Melville Island, about 80km (50 miles) north of the mainland city of Darwin. The cause of the crash is under investigation.
All 20 survivors were taken to the Royal Darwin Hospital and 12 had been discharged by Monday, Northern Territory Chief Minister Natasha Fyles said.
Fyles said she would not detail the conditions of the eight who remained in hospital out of respect for them and their families.
Australia’s defence ministry said the crash happened during the annual Predator Run exercises involving the militaries of Australia, the United States, East Timor, Indonesia and the Philippines. About 2,500 troops are taking part.
Australian Prime Minister Anthony Albanese called it a “tragic” incident.
“Our focus as a government and as a department of defence is very much on incident response and on making sure that every support and assistance is given at this difficult time,” he said.
Australian personnel were not involved, Albanese said.
US President Joe Biden also expressed his “deepest condolences” to the families of the Marines who were killed. “We are praying for those who also suffered injuries,” Biden said in a social media post late on Sunday.
Jill and I send our deepest condolences to the families of the Marines who lost their lives in this deadly crash. We are praying for those who also suffered injuries. https://t.co/sztAUHbpeB
— President Biden (@POTUS) August 28, 2023
The US and Australia, a key ally in the Pacific, have been stepping up military cooperation in recent years in the face of an increasingly assertive China.
“Australian and US personnel have stood shoulder to shoulder for more than a century,” Albanese and Australia’s Defence Minister Richard Marles said in a statement.
“This incident is a reminder of the significance of the service undertaken by our personnel and those of our partner nations.”
Four Australian soldiers were killed last month when their helicopter crashed into the sea off the coast of Queensland.
The aircraft had been taking part in Talisman Sabre, a joint military exercise involving a total of 13 countries, including the US, Australia, Japan, France and Germany, and more than 30,000 personnel.
Ospreys are tilt-rotor aircraft that combine the features of both helicopters and turboprop planes, according to the US Air Force.
It has two swivelling engines positioned on fixed wingtips that allow it to land and take off vertically, but also move at faster speeds than a conventional helicopter.
The Osprey aircraft’s safety record has repeatedly come into question after a series of fatal incidents.
In June last year, all five Marines on board an Osprey were killed when it crashed in the California desert near the Arizona border.
In March of that year, four Marines were killed when an Osprey crashed near a Norwegian town in the Arctic Circle during a NATO exercise.
In 2017, three Marines were killed when an Osprey crashed after clipping the back of a transport ship while trying to land at sea off Australia’s north coast.
Al Jazeera and news agencies