The US Marine Corps said on Saturday a search and rescue operation was underway for three service members involved in an aviation "mishap" off the east coast of Australia, with 23 others rescued.

The incident occurred off the coast of Shoalwater Bay, in the state of Queensland, at around 4 p.m. local time on Saturday. 

An MV-22 Osprey tilt-rotor aircraft with 26 people onboard was conducting regularly scheduled operations when it entered the water, the III Marine Expeditionary Force based in Okinawa, said in a statement. 

The cause of the accident is still unknown.