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.
The mother of Mr Dorsett and Ms Goodchild has told the Courier Mail the accident has devastated her family.
"I have three children and have lost two of them today - my whole family has been wiped out," Kim Dorsett told the Courier Mail.
Dreamworld visitors described the chaos after the accident at 2.20pm.
"It all happened so fast. One minute we were just about to get on the ride and the next there was this little girl screaming and we were just trying to comfort her," Lia Capes told the Courier Mail.
Several parkgoers claimed the ride had broken down at least twice earlier in the day and police said those claims would form part of the investigation.
The deaths had an immediate financial impact on the park's owners Ardent Leisure, as it shares fell 7.8 per cent on news of the tragedy.
Queensland Ambulance senior operating officer Gavin Fuller said on Tuesday the victims suffered fatal injuries and couldn't be revived despite several crews attending the scene.
Thousands of patrons left the park in shock following the tragedy.
A coronial investigation into the cause of the accident and the deaths is underway, with workplace health and safety officers and police forensic crash investigators also involved.
Dreamworld chief executive Craig Davidson said their thoughts were with the families and loved ones of those killed.
The company released a statement on Tuesday night saying "the entire Dreamworld team is devastated and shocked by this incident."
The Thunder River Rapids Ride is currently Australia's only river rapids ride and opened in December 1986.
Dreamworld's Rocky Hollow Log Ride was shut down in April this year when a man fell from the ride and nearly drowned.
