An Australian union expressed safety concerns last year about the Gold Coast theme park where four people died yesterday.
One of the four who died in yesterday's tragedy was a New Zealander, believed to have been a long-term resident of Australia, officials have confirmed.
Australian media has reported the three other victims were Kate Goodchild, 32, her brother Luke Dorsett, 35, and Mr Dorsett's partner Roozbeh Araghi, 38.
Early investigations suggest water pushed one raft into another on the Thunder River Rapids Ride yesterday and one of the rafts tipped over, throwing two people out and trapping another two inside.
AWU Queensland secretary Ben Swan said the union lodged a complaint about safety 18 months ago with park owner Ardent Leisure, after a separate industrial incident.
He said the union became increasingly concerned about safety at Dreamworld as it investigated that incident, which did not involve Thunder River Rapids ride.
"I think people's priorities should rightly be on taking care of the situation that immediately exists and looking after the people that have been involved in that, but we did hold some very grave concerns about safety of equipment and the operation of equipment at that site," he said.
More on the Dreamworld indicent
Series of accidents at park
Queensland authorities are promising a thorough investigation into the latest incident at Dreamworld, which follows less serious accidents at the same park.
Earlier this year, a man nearly drowned after he was thrown from the log ride at Dreamworld. Emergency service said he was was helped out of the water and later taken to hospital with "facial lacerations".
A helicopter joy flight crashed into Dreamworld's carpark in June 2009 but, incredibly, the four passengers and the pilot survived with relatively minor injuries. Dreamworld has not run joy flights since the incident.
Things have also gone wrong at other Gold Coast theme parks.
Several people had to be evacuated from a roller-coaster at Sea World during the September school holiday season this year when it stalled mid ride.
And in January 2012, the Green Lantern rollercoaster at Movie World was stopped twice in one day, leaving passengers stuck for up to 70 minutes. In March 2015, 13 people were stuck on the Green Lantern rollercoaster, six for about three hours, after a wheel dislodged in March of 2015.
The Gold Coast is probably New Zealand's most popular short-haul family holiday destination, according to a House of Travel spokesperson, who said nearly 190,000 New Zealanders travelled there in the year to last March.
'There were kids onboard screaming'
Police said yesterday the four who died on the Dreamworld ride were two women aged 42 and 32, and two men aged 38 and 35.
Todd Reid, an inspector with Queensland Police, would not confirm whether any of the adults who died were related, saying police were in the process of notifying their families.
Asked if there were any earlier problems with the ride, he said, "I'm not aware, but that will be part of the investigation."
"[The ride] had sustained some sort of malfunction causing two people to be ejected ... another two people were caught inside the ride," Queensland Ambulance Service senior operations supervisor Gavin Fuller said.
The ride, meant to simulate going over river rapids, uses round floating devices that seat six, and can reach speeds of 45 km/h. It is described by Dreamworld as a "moderate thrill" attraction for those older than two.
Witnesses recounted the scene on television.
"There were kids onboard screaming while their mum was trapped under. I'd rather not talk about what I saw," one unidentified man told Australia's Channel 9.
Lia Capes said she was just about to go on the ride when she saw people running out, crying.
"We saw little girl and we believe it was her mum because it was just her and her little sister that was an infant," Ms Capes said.
"I was speaking to one of the guys and he said it was the raft or the boat thing in front of him, the whole thing flipped and everyone was screaming."
Visitors to the theme park south of Brisbane said they had seen repairs to the ride before the accident, but a Dreamworld spokeswoman told Reuters she was unable to confirm the reports.
Queensland Premier Annastacia Palaszczuk said she took her family on the rapids ride earlier this year.
"This is a ride that thousands and thousands of families have been on and to have this happen ... we've just got to get to the bottom of it.
She said while the theme park had a good safety record, there would be a thorough investigation.
"We want to leave no stone unturned to get to the bottom of this. We want to ensure that nothing like this ever happens again," she said on Tuesday.
"Safety needs to be a number one priority and what we've seen today is perhaps the worst tragedy in a theme park in my living memory."
Australian Prime Minister Malcolm Turnbull also pleged a full investigation to determine the cause of the accident.
Tuesday's tragedy is one of the worst theme park accidents on record.
Earlier incidents include eight teenagers killed in a 1984 fire at the Six Flags Great Adventure amusement park in New Jersey in the United States; seven dead in Sydney's Luna Park ghost train fire in 1979 and six people killed by a failed simulated rocket launch in Shenzhen, China, in 2010.
- RNZ / ABC / Reuters