A horrified onlooker has described seeing a woman's legs and hips dangling from an amusement ride seconds before she plummeted 30m to the ground.
The 25-year-old remains in a serious but stable condition at Cairns Hospital after she fell from a carriage on the Hangover ride at Cairns Showfest on Saturday.
Bonnie Thistle was standing nearby when the tragedy unfolded.
"It'd only just gone up in the air," she told NCA NewsWire on Monday.
"It started coming down while she was coming out of it."
Thistle said she turned to her partner and said, "This chick's already out of the ride."
"Her legs and hips were already out," she said.
"I literally looked away for two seconds and when I looked back she was gone.
"The seat was empty."
Thistle said she walked over to the ride to see the woman lying on her back at the base of it.
She was bleeding from her head," she said.
"It was horrific."
Thistle, who has a 3-month-old child, said she stopped going on amusement attractions when she was younger after she almost fell out of one.
"I'm a really petite person so I slide really easily," she said.
Queensland Premier Annastacia Palaszczuk described Saturday's incident as dreadful.
"There's a duty of care of course that all ride operators owe to anybody that goes on to those rides," she said.
"There will be a thorough workplace health and safety investigation into that and I look forward to seeing those results."
In a statement on its website, Showfest organisers described being "deeply shocked and saddened" by the incident.
They confirmed they were working with investigators to get to the bottom of what happened.
"We have been given absolutely no details of the young lady, or her family, or any specific reasons for the cause of the accident," they wrote.
"However, the organisers would like to reach out to express their deep concern, and are hoping the lady's recovery is paramount."
Millions of people in Queensland and New South Wales have been warned to brace for days without power after Tropical Cyclone Alfred makes landfall later this week.