A Kiwi woman's 10-year-old son watched her die in a horrific accident at a Gold Coast theme park.

LISTEN ABOVE: 9 News Brisbane reporter Jessica Millward speaks with Chris Lynch

Cindy Low, 42, originally from Kawerau, died yesterday at Dreamworld along with three others when their Thunder River Rapids ride flipped, trapping the victims in machinery below. 

The mother-of-two lived in Sydney for at least a decade with her Kiwi husband, Mathew, who was originally from New Plymouth. 

The couple were on holiday on the Gold Coast with their son and daughter.

Low was sitting next to her 10-year-old, Kieran, on the ill-fated ride. Her husband and 6-year-old daughter were not on the ride.

It is understood Kieran was the last person to see his mother alive.

He was one of two children who survived the horrific accident. He was admitted to Gold Coast University Hospital yesterday with his father at his bedside.

However a hospital spokeswoman told the Herald today he had been discharged last night.

Shocked New Zealand relatives are currently on their way to the Gold Coast to support the family. 

• Ex-Kawerau woman killed in Dreamworld tragedy named

A witness told the Daily Mail that children on the ride screamed, "while their mum was, like, trapped under [the raft]."

Initial investigations suggest a six-seater raft collided with an empty raft that had become stuck near the end of the ride.

It's believed to have then flipped, killing four adults.

In a press conference yesterday, a Queensland Ambulance Service spokesman said all victims suffered injuries that were "incompatible with living".

He said two people were "ejected" from the ride, and two others were trapped.

Emergency services were called to the scene about 2.20pm Queensland time, to find park staff administering first aid to the victims.

New Zealand's Ministry of Foreign Affairs and Trade (Mfat) has now been advised by Queensland police that a New Zealand woman was one of the victims.

This morning, a Queensland police spokesman told the Herald none of the victims lived at New Zealand addresses.

Two men, aged 38 and 35, and two women, aged 42 and 32, died in the accident.

The other victims have been named as Kate Goodchild (nee Dorsett), 32, her brother Luke Dorsett and his partner Roozi Araghi.

Goodchild's daughter is understood to have been one of the children thrown to safety from the raft. She screamed in horror as she watched her mother die, the Daily Telegraph reported.

Meanwhile, two other Kiwi's were at Dreamworld when the incident unfolded.

New Zealanders Kaylah Walker, 25, and her mother Lisa Walker, told Fairfax the ride was not working earlier in the day.

"Earlier in the day it had broken down," Lisa Walker said.

"It had broken down and we went back a couple of times to this particular ride.

"We were standing on the bridge watching and the water had stopped.

"There was no rapids."

The incident happened about 10 minutes after they walked away from the ride.

She described the Thunder River Rapids as "one of the most tame rides in the park".

"Unless you are a wee tiny tot," Lisa said.

A police investigation is ongoing and the deaths have been referred to the coroner.

Australia correspondent Donna Demaio said there were reports of problems on that particular ride before the accident.

One witness said they'd been waiting for half an hour because engineers were working on the ride, Demaio reported.

"They drained all the water out, then they had to refill it, and then people were allowed to go back on the ride."

"This witness actually relayed that they were stuck waiting to get on this ride for at least 30 minutes, just a few hours before this incident happened."

A New Zealand woman who was at the amusement park last week told the Heraldshe got stuck on the ride.

"Management blamed it on water pumps and after 20 minutes' wait we were evacuated by exiting off a steep ramp," she said.

"I believe this was not a one-off accident and could have been avoided."

Dreamworld in Queensland is closed until further notice.