"Everyone was screaming": Dreamworld tragedy claims four lives.

Four adults — two men and two women — have been killed in an incident at Dreamworld on the Gold Coast, police have confirmed. It is reported the deceased adults were aged between 32 and early 40s.

Emergency services were called to the Gold Coast theme park at around 2pm this afternoon amid reports of an incident on the Thunder River Rapids ride.

Nine News reports helicopter footage revealed the ride’s six-seat rafts flipped on the ride’s conveyor belt, which typically returns guests to the disembarking area.

In a press conference this evening, Dreamworld CEO Craig Davidson announced the theme park was closed until further notice, adding that Dreamworld is working closely with police and authorities.

He said the “tragic deaths of four people” have left him and his employees “deeply shocked and saddened”.

“Our hearts and our thoughts go to the families involved and their loved ones,” he told the group of media personnel.

A police spokesperson said workplace health and safety officers, as well as the state coroner and forensic crash unit, are in attendance at the scene.

“This matter is now a coronial investigation and being investigated by workplace health and safety,” he said.

Until the deceased adults’ next of kins are contacted, and “due process” is taken, the policeman said it would be “inappropriate” to identify the victims.

“Dreamworld is working as quickly as possible to establish the facts around the incident and is working closely with emergency authorities and police to do this,” a statement from Dreamworld read today.

“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.”

Eyewitness Lia Capes was waiting to go on the ride when she saw people running from it, screaming and crying.

“We saw [a] little girl and we believe it was her mum because it was just her and her little sister that was an infant,” Ms Capes told ABC News.

“I was speaking to one of the guys and he said it was the raft or the boat thing in front of him, the whole thing flipped and everyone was screaming.”

She added that Dreamworld staff hurriedly evacuated the area.

“The little girl that was crying, they asked us to take her because we distracted her, she was bawling her eyes out,” she said.

“[Then] people that worked here took her and her little sister away.”

Ambulance, firefighters and rescue crews attended the scene, where one person was unconscious and was being given CPR, the Brisbane Times reports.

One man, Tim Oxley, claims he has complained to Dreamworld staff in the past about the Thunder Rapids ride.

US Olympic athlete Matthew Centrowitz who alighted the ride shortly before the incident claimed via Twitter that two people were ‘trapped’, however this is yet to be confirmed.

Gold Coast mayor Tom Tate expressed his sympathies for the families of those involved in the accident this afternoon.

“This is a very sad day for our city,” he wrote on Facebook.

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

“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.”

Others shared their heartbreak and shock on Twitter, with one Adelaide woman expressing concern that her family members had attended the park today.

The Thunder River Rapids ride reportedly opened in December 1986, and requires riders board one of several six-person rafts.

Once the rafts are dispatched, they travel in a queue to a cave. Upon exiting, they quickly descend down the main rapids section, which runs alongside a large water catchment.

Children as young as two years old are permitted to ride the Thunder River Rapids ride.