The MRH-90 helicopter was conducting joint military training as a part of Exercise Talisman Sabre when it crashed near Hamilton Island about 10.30pm on Friday.
Talisman Sabre director Damian Hill told reporters on Saturday the missing crewmen came from the 6th Aviation Regiment based at the Holsworthy Army barracks in Sydney.
Brigadier Hill said the families of the four crew members had been informed of the accident.
Premier Chris Minns confirmed one of those feared dead following the crash was the son of a senior NSW police officer.
"(They're) a family that's given so much to the people of this state of this country," he told Sky News on Sunday.
"I can only imagine what they're going through today. It's just devastating."
Queensland Police Assistant Commissioner Douglas McDonald said some debris from the helicopter had been recovered on Saturday.
He urged any members of the public who found further crash material on the beaches around Hamilton or Dent islands to contact police.
"At this time we have located a number of items of debris that would appear to be from the missing helicopter," Mr McDonald said.
"Can I encourage if any members of the community are on those beaches and come across anything that they might think is debris related to this particular incident, if they can contact police immediately and don't touch the items."
Brig Hill said specialist navy divers would be deployed on Sunday when additional ships arrived with sonar equipment.
"The water is quite deep in and around the potential impact area," he said.
"HMAS Huon has some of our more experienced divers should we need to look under the water for wreckage as the search and rescue continues."
The Talisman Sabre training operation involves defence forces from Australia, the United States and other allies.
The joint exercises, which are mostly being held in regional Queensland, resumed late on Saturday in the Northern Territory and West Australia after an initial pause following the accident.
Brig Hill confirmed 47 other MRH-90 helicopters had been grounded until further notice.
It is the second time an Australian MRH-90 has been involved in an emergency this year after a Taipan ditched into waters off the NSW south coast in March.
The helicopter has earned a reputation as unreliable in recent years, with malfunctions and technical issues forcing several earlier groundings of the fleet.