The bodies of four people killed at the Dreamworld theme park on the Gold Coast last week have been released to families for burial, Queensland police have confirmed.

Cindy Low, Kate Goodchild, her brother Luke Dorsett and his partner Roozbeh Araghi died when their raft on the Thunder River Rapids ride flipped over on Tuesday afternoon.

Two children who were also in the raft survived the accident.

In a statement on Monday afternoon, the Queensland Police Service said post-mortem examinations had been concluded.

The QPS is continuing to investigate the fatal accident on behalf of the coroner.

“At the conclusion of investigations police will submit a comprehensive report to the coroner,” the statement said.

“As this is a coronial investigation, police are not able to provide investigative updates.”

Police said they would advise the media when investigations and examinations at Dreamworld were complete.

But a report for the coroner is still expected to take some time.

Staff back at theme park

Earlier on Monday, police were seen removing rafts from the Thunder River Rapids ride as part of their ongoing investigation.

Dreamworld CEO Craig Davidson also announced that 200 staff had returned to work as part of a “cautious and staged” recovery.

He said it was optional for staff to return to work on Monday.

“Staff who are at work today are here because they want to be,” he said.

“Returning to work has not been compulsory. It is for those staff who want to come back and help the park and support their colleagues.”

Mr Davidson said last week Dreamworld would not reopen until funerals had been held for all four people who were killed.

Police have been removing rafts from the Thunder River Rapids ride as part of their investigation. Photo: ABC