Mother's ominous Dreamworld warning: "Someone will get seriously injured or killed one day."

An ominous warning about the safety of the rides at Dreamworld has emerged in the wake of a tragedy that took four lives on Tuesday afternoon.

After visiting the popular Gold Coast tourist attraction just fifteen days prior to Tuesday’s accident, Gold Coast mum Tracey Christensen wrote on Facebook, “Someone will get seriously injured or killed one day.”

Brother and sister 35-year-old Luke Dorsett and 32-year-old Kate Goodchild, Dorsett's partner, 38-year-old Roozi Araghi and an unnamed 42-year-old woman were all killed yesterday, when the Thunder River Rapids ride malfunctioned.

Also on the ride was Kate Goodchild’s 12-year-old daughter and the 10-year-old son of the 42-year-old woman, thought to be from New Zealand.

Writing on the Dreamworld Facebook page on 10 October, Christensen complained of issues with multiple rides and said that at one point while on The Claw, her child's safety buckle came undone "right up in the air."

"I told the attendants and they didn't listen," Christensen's post continued. "I went and told the manager and he said he will call someone to go have a look, yet they continued to let people on the ride and keep operating."

Unhappy with the clear safety breach, Christensen pushed the manager on the issue.

"I went back to the manager and questioned it and he tells me that that belt buckle is an added safety feature dreamworld added to the seats, so if they come undone they are still safe. There must have been a reason they added those belt buckles," she reasoned.

Experiencing "operational issues" on the Tower of Terror, Puss in Boots, Wipeout and The Log rides, and her child's brush with terror on The Claw, Christensen reasoned, "I paid $400 to get yearly passes and all I want now is my money back because having 5 rides with operational issues is not good enough. Someone will get seriously injured or killed one day."

The four adults were killed when 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 on Tuesday evening, Dreamworld CEO Craig Davidson announced the theme park was closed until further notice, adding that Dreamworld is working closely with police and authorities.

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