Four adults killed on water ride at Australian theme park

BUNDABERG, Australia - Dreamworld is Australia's largest theme park, but it quickly became the sight of a horrific nightmare when four adult park guests were killed.

The accident happened on Thunder River Rapids, a white water rafting experience down a turbulent water track. It appears a raft with six people collided with an empty raft stuck on the conveyor belt near the end of the ride.

“Causing two people to be ejected from a ride," according to Gavin Fuller, acting senior operations supervisor for Queensland Ambulance Service. "Another two people were caught inside the ride."

Two victims were crushed to death under the raft while the other two were trapped in the conveyor belt under water. Two children were also knocked out of the ride. Their injuries are not life-threatening.

“We are deeply shocked and saddened by this," says  Dreamworld’s CEO, Craig Davidson. "The park is closed and Dreamworld is working closely with police and emergency services authorities to establish the facts around the incident.”

Park staff tried to rescue the riders to no avail. Two men and two women are dead.

Thunder River Rapids is billed as family-friendly. Children as young as 2 years old are allowed to ride with an adult.

Dreamworld opened in Queensland in 1981. It includes about 50 rides, animal attractions, shows and shops. Everything's been shut down, indefinitely. Authorities say this investigation could take several weeks.