Four people have died in an accident on the Thunder Rivers Rapids family ride at Dreamworld on the Gold Coast.

Two men and two women ranging in age from 32 through to their early 40s died after the theme park ride malfunctioned this afternoon, Queensland Ambulance Services spokesman Gavin Fuller said.

“One of the rides had sustained some sort of malfunction causing two people to be ejected from the ride,” Mr Fuller said. “Another two people were caught inside the ride – two males and two females,” Mr Fuller said.

Aerial footage shows one of the ride’s six-seat circular rafts flipped on the conveyor belt that usually delivers them back to the boarding and disembarking area.

9NEWS understands the victims were possibly from the same family and may have been visiting from interstate.

Mr Fuller said park workers were providing first aid when paramedics arrived, and first responders had been “deeply affected” by the accident.

Dreamworld CEO Craig Davidson said his company was “shocked” by the accident.

“Dreamworld confirms that at approximately 2.20pm today, an incident occurred on the Thunder River Rapids Ride that resulted in the tragic deaths of four people,” he said. “At this stage the park is closed and Dreamworld is working closely with police and emergency services and authorities to establish the facts around the incident.

“We are deeply shocked and saddened by this and our hearts and our thoughts go to the families involved and to their loved ones.”

Queensland Police Service Inspector Tod Reid said a crime scene had been established and workplace health and safety officers, forensic crash unit officers and the state Coroner were attending.

“Police were called to the site at Coomera around 2.20pm following reports that a number of people had been injured by a conveyor belt,” a police statement read.

“Four adults have been confirmed as being deceased.” One witness told 9NEWS that she had been on the same ride about 10 minutes before the accident.

“It wasn’t long before that we were on it, and then the park started getting shut down and we saw the helicopters,” she said outside the park.

“We were walking out and heard that the mother, the father and the uncle got seriously injured and possibly died.”

According to Dreamworld, visitors as young as two years old can ride the Thunder River Rapids, but under-fours must be accompanied by an adult.

Gold Coast Mayor Tom Tate issued a statement following the accident, calling the day “a very sad day for our city”.

“Our thoughts are with the families of those affected – and the emergency staff in attendance,” he wrote.

“I urge everyone to show the respect needed as the relevant authorities undertake investigations in to what has occurred.

“A truly sad day for all.”

Dreamworld shut down after the accident, and visitors could be seen gathered outside the park at 4pm AEST.

Any witnesses have been urged to contact Dreamworld staff.

News courtesy-9 News