Debris has been found after an Australian military helicopter crashed off the coast of Queensland, leaving four people missing, police say.
The incident took place during US-Australian exercise off Lindeman Island on Friday night.
Defence Minister Richard Marles said a search and rescue mission was immediately launched.
"The four air crew are yet to be found," Marles said during a press conference on Saturday morning.
He said that the MRH-90 Taipan helicopter crashed near the island, in the Whitsundays, at about 22:30 local time (12:30 GMT).
"Our hopes and thoughts are very much with the aircrew and their families," he said, adding that "we desperately hope for better news during the course of the day".
"These are early days and there will be much more information to be provided about this incident," he said.
Speaking at the same press briefing, the Chief of the Defence Force Angus Campbell said it was "a terrible moment".
"Our focus at the moment is with finding our people and supporting their families and the rest of our team," he said.
He said he appreciated the support provided by civil agencies, the police, the public and "our US allies" to assist the search and rescue operation so far.