SYDNEY - At least three people have been killed on a ride at Australia's biggest theme park, the organisation said on Tuesday.

The incident took place at Dreamworld, on the Gold Coast tourist district in Queensland state, police said on their official account on social network Twitter.

"Dreamworld is working as quickly as possible to establish the facts around the incident," theme park officials said in a statement, adding that they were working closely with emergency authorities and police.

"Dreamworld's focus and priority is with the families of those involved in this tragedy and will be providing an update to the public as soon as information becomes available."

In an earlier tweet, Queensland police said four people were critically injured. Media said the accident happened on a ride known as the "Thunder Rapids River Ride".

Police said they would provide more details at a news conference later on Tuesday.