Dreamworld will remain closed on Wednesday while police examine how four people were killed on a 30-year-old water raft ride at the Gold Coast theme park.
Brother and sister Luke Dorsett, 35, and Kate Goodchild, 32, and Canberra man, and Mr Dorsett's partner, Roozi Araghi died in the catastrophic accident.
The three and another woman were victims of a conveyor belt malfunction at the Gold Coast park when their raft flipped on the Thunder River Rapids ride on Tuesday afternoon.
Two were thrown clear of the ride while the other two were stuck in the ride itself.
Two girls aged 10 and 13, who were also on the ride, are being cared for in hospital as dozens of detectives try to work out what went so horribly wrong.
Police have not confirmed if the children are related to the two men and two women who died.
Queensland Police Assistant Commissioner Brian Codd told reporters the incident had happened at the end of the ride when the boat, or flume, containing the victims crashed into another boat and flipped.
"We know that an occurrence has seen that particular flume be turned over and flipped, resulting in it falling back on top of those persons and those persons being variously caught in machinery - and I don't want to go into too much graphic detail," he said.
"I guess the fortunate thing here is that the two children managed to escape that disaster and, unfortunately, the four adults did not."
He said it was a "miracle" the two girls had managed to survive.
Assistant Commissioner Codd said police would conduct a thorough investigation with the Coroner that would take as long as it needed to take.
