US military aircraft and boats are scouring waters off Australia's east coast Saturday for three Marines involved in what the Marines Corps is calling a "mishap" with an MV-22 aircraft.
Twenty-three of the 26 personnel on board have been rescued, the US Marine Corps said.
Small boats and aircraft from the 31st Marine Expeditionary Unit and Bonhomme Richard Expeditionary Strike Group are carrying out the search and rescue operation, according to the Marine Corps.
The US military has been in the area for training exercises with the Australian military. The MV-22 is a vertical-launch aircraft, also known as an Osprey.
"The aircraft involved in the mishap had launched from the USS Bonhomme Richard (LHD 6) and was conducting regularly scheduled operations when the aircraft entered the water," the Marine Corps said in a statement.
Crew on board the Bonhomme Richard were performing water training exercises Saturday, according to the ship's Facebook page. The exercises were a follow-up to joint military training between US and Australian forces that wrapped up last week.
Marine authorities are investigating the incident. White House Chief of Staff John Kelly has briefed President Donald Trump on the situation, a White House spokesman said.
Australian Prime Minister Malcolm Turnbull has also been made aware of the operation in Shoalwater Bay. Australian Defense Minister Marise Payne said in a statement she had spoken to US Defense Secretary James Mattis to offer Australia's support in "anyway that can be of assistance."
Australian authorities said no Australian personnel were on board.
The recent joint military exercise took place largely in Shoalwater Bay and involved more than 30,000 US and Australian personnel, according to Australian Defense Department.