The US military has suspended a search and rescue operation for three US Marines who went missing after an aircraft “mishap” off the eastern coast of Australia, officials said Sunday.

Twenty-three of the 26 personnel who had been on board the aircraft have been rescued since the incident, which occurred around 4 p.m. local time on Saturday, according to officials.

“Operations have now shifted to recovery efforts,” the Marine Corps said in a statement. “The transition comes after teams led continuous sustained search efforts supported by aircraft and ships. As the sea state permits, recovery efforts will be conducted to further search, assess and survey the area, in coordination and with assistance from the Australian Defence Force.”

The circumstances surrounding the mishap, which involved an MV-22 Osprey, are still under investigation, the Marine Corps said.

The aircraft was conducting “regularly scheduled operations” when it entered the water, officials said in an earlier statement.

“The aircraft involved in the mishap had launched from the USS Bonhomme Richard and was conducting regularly scheduled operations when the aircraft entered the water,” the statement said. “The ship’s small boats and aircraft immediately responded in the search and rescue efforts.”

A White House official said President Donald Trump was briefed by John F. Kelly, the White House chief of staff, on the situation.

Australian Defense Minister Marise Payne said the incident occurred off the coast of Queensland’s Shoalwater Bay, which is home to a military training area.

Payne said no Australian military personnel were on board the aircraft.

“The United States are leading the search and recovery effort,” she said. “I have briefed Prime Minister Turnbull and spoken with [US Defense] Secretary [James] Mattis this evening to offer Australia’s support in anyway that can be of assistance.”

The Australian Broadcasting Corporation reported the aircraft had been in Queensland as part of a joint US and Australian training exercise that ended July 25.

Some 1,250 Marines touched down in Australia in April on a six-month deployment to conduct training exercises with local troops and visiting Chinese forces. Thirteen US aircraft were sent to Australia as part of the deployment, including the tilt-rotor Ospreys, Reuters reported.

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