2016: Channel 9 news report on the horrific accident at Dreamworld.
Dreamworld visitors said there had been problems on the ride that killed four people earlier in the day and engineers were called in, according to reports.
"We were waiting there for about half an hour and engineers had to come," a woman told Nine News of the earlier incident.
"They drained all the water out and then had to refill it back up, and then we were allowed to go. But, yeah, we were stuck there for about 30-40 minutes at least."
When asked at a press conference if there had been incidents on the ride earlier in the day, a police spokesman said: "I'm not aware, but that will be part of the investigation and that will be one of the aspects we will be looking at."
Dreamworld describes the three decade old Thunder River Rapids, at the centre of the tragedy, as a ride down a "foamy water track" at up to 45km/h.
Police confirmed four people died on the ride at the Gold Coast's biggest theme park about 2.10pm Queensland time on Tuesday.
Gavin Fuller of Queensland Ambulance said two of the victims were "ejected" after a "malfunction" on the ride, while two others were caught inside.
The dead were aged from 32 to early 40s. Mr Fuller said their injuries were so severe they were "incompatible with life".
One of Dreamworld's most popular rides, Thunder River Rapids opened in 1986 and is situated in the "Town of Gold Rush" portion of the park that attracts visitors from across Australia.
On the theme park's website, Dreamworld encourages thrill seekers stating, "all aboard for white water rafting!" The park boasts of "turbulent rapids" through "Gold Rush country".
Listed as a "moderate thrill" with a maximum of six riders, children only have to be more than two years old to board the ride but under fours must be accompanied by an adult.
Circular rafts of six seats are used on the ride which spin and tumble along a white water course of raging rapids. People are strapped in not by the usual heavy harness but by loose straps around the waist, potentially so riders can escape if the cars flip in the water.
Theme park review website Parkz classes Thunder River Rapids as "good" with a rating of 72 out of 100. But it is listed as relatively modest when it comes to "intensity".
In the past, riders could reportedly board and dismount the boats while they were still moving but this was halted due to safety concerns.
In this image made from video, rescue vehicles are parked outside Dreamworld on the Gold Coast. Photo / ABC via AP
The Thunder River Rapids Ride is currently Australia's only river rapids ride and opened on December 11, 1986, reports the Gold Coast Bulletin.
Riders board one of several six-person circular rafts.
The raft is dispatched and the riders travel back past the ride's queue and into a cave.
Upon exiting the cave, riders experience the main rapids section of the ride. This section runs alongside a large water catchment which powers both the Thunder River Rapids Ride and the Rocky Hollow Log Ride.
