By Tom Westbrook and Jane Wardell
SYDNEY, Oct 26 (Reuters) - Forensic police were examining a river rapids ride at Australia's biggest theme park on Wednesday after four people were killed when it apparently malfunctioned, throwing two people off and trapping the other two inside.
Tuesday's tragedy at the Thunder River Rapids Ride at Dreamworld on the Gold Coast, the main tourist district in the northeastern state of Queensland, ranks among the world's deadliest theme park accidents.
"Our thoughts and prayers are with the families of those whose lives were lost in this terrible accident," Australian Prime Minister Malcolm Turnbull said on Australian Broadcasting Corporation radio on Wednesday.
The victims, two men aged 33 and 38 and two women aged 32 and 42, all lived in Australia, police said. The New Zealand government confirmed one of the victims was a New Zealand citizen. Two children who were also on the ride were being treated for injuries in hospital, Queensland State Premier Anna Palaszczuk said.
Police have not yet confirmed the relationship of the hospitalised children to any of the adults. Local media reported that a brother and sister were among the fatalities.
Forensic police and workplace safety authorities, who are also checking CCTV footage, will prepare a report for the state coroner, who will then decide if any charges should be laid over the incident.
Shares in park owner and operator, Ardent Leisure Group AAD.AX , dropped 7 percent in the final hour of trading on Tuesday after the accident, having been little changed for most of the day.
The ride, meant to simulate going over river rapids, uses round floating devices that seat six, and can reach speeds of 45 kph (28 mph). It is described by Dreamworld as a "moderate thrill" attraction for those older than two.
Visitors to the theme park, 48 km (30 miles) 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 those accounts.
Asked on Tuesday whether there were any earlier problems with the ride, Todd Reid, an inspector with Queensland Police, said, "I'm not aware, but that will be part of the investigation."