Four people have been killed at an Australian theme park

Updated: 

Four people have been killed in an accident at a theme park on Australia's east coast.

Two men and two women died on the Thunder River Rapids ride at Dreamworld, a popular attraction on the Gold Coast, Queensland, state police officer Todd Reid told reporters.

A malfunction on the ride, which whisks people in circular rafts along a fast-moving, man-made river, caused two people to be ejected from their raft, while two others were caught inside the ride, said Gavin Fuller, an officer with Queensland Ambulance Service.

He did not know if the two victims who were caught in the ride were trapped underwater, or caught up in the machinery.

Dreamworld
(Channel 9 via AP)

Park staff administered first aid to the victims, but their injuries proved fatal, Fuller said. The victims were in their thirties and early forties.

Dreamworld chief executive Craig Davidson said the park was working with police to try to determine what went wrong. The park was closed following the accident.

Dreamworld
(Australian Broadcasting Corporation via AP)

Thunder River is considered one of Dreamworld's tamer, family-friendly rides, and is open to children as young as two.

Australian prime minister Malcolm Turnbull said there would be a thorough investigation into the cause of Tuesday's accident.

"Theme parks are a place for family fun and happiness, not tragedy," he said.