A desperate David Goodchild watched on helplessly as his wife Kate died in front of his eyes during the horrific tragedy on the Thunder River Rapids ride at the Dreamworld theme park on the Gold Coast.
Mr Goodchild was standing at the end of the ride with his baby daughter Evie, watching the raft carrying Kate and their elder daughter Ebony, 12, as well as Kate's brother and his partner.
The raft, containing six people in all, was coming up the conveyor belt to the drop-off point when it hit the raft in front of it and suddenly flipped over onto its back.
There was no warning. Only the screams of the two children on the raft, followed by terrified shrieks from the four adults and cries of horror from the crowd waiting to board the ride.
Acting on a mixture of panic and instinct, Mr Goodchild threw his wallet and phone on the ground and rushed to try to rescue his wife and daughter.
But it was no use.
Ebony was thrown clear and somehow survived. But Kate was killed almost instantly.
Not far away, according to police reports, Mathew Low was enjoying the day with his daughter Isla, 6.
Suddenly he heard screams and cries of panic from the direction of the Thunder River Rapids ride, and he broke into a run.
His wife, Cindy, 42, was with their son Kieran, 10, and had gone to try out the whitewater attraction.
Mr Low arrived too late.
Like Ebony, Kieran had miraculously been thrown from the stricken raft and somehow survived.
But Cindy was already dead.
The other two adults on the raft also perished - Ms Goodchild's brother Luke Dorsett, 35, and his partner Roozi Araghi, 38.
Last night, Mr Goodchild's father Graham said his son was so distraught he could not even talk about what happened after David returned to his family home in Canberra with Ebony and baby Evie.
"They haven't even told us completely what happened but I know that tonight there are two very traumatised children coming back home," he said.
Mr Low had been at his son Kieran's bedside at Gold Coast University Hospital before he was released yesterday morning.
The family, originally from Kawerau on New Zealand's North Island, had been living in Sydney and more recently on the Central Coast for about 10 years, and their relatives were last night travelling from New Zealand to Mr Low and his children.
Mr Low, a business systems specialist for hearing aid company Oticon, was in a state of "intense grief" his workmates said.
"The family are traumatised, and kindly request that their privacy be respected as they try to come to terms with this tragic loss," a statement from the North Ryde company said.
Kawerau mayor Malcolm Campbell said the Lows came from "quite a large family" and the town was stunned.
"It's a pretty tight-knit community here and we'll all be gathering around and supporting the family as best we can," Mr Campbell said.
Mr Araghi's grieving father, Behrooz Araghi, found out about the tragedy from a news report
He said his son and the Goodchilds had been in Queensland for a wedding before their fateful decision to squeeze in the trip to the Gold Coast theme park.
"We've lost one son - the mother of my son's partner lost two," Mr Araghi, who lives in Sydney, said.
Mr Araghi's brother Simon took to Facebook to make an emotional tribute to his "most loved baby brother". "On behalf of my brother Dory and my family, I confirm the loss of our most loved 'baby' brother Roozi and his partner Luke and our lovely Kate," Simon wrote.
Labor senator Sam Dastyari said he grew up alongside Mr Araghi and his father Behrooz had helped bring the Dastyari family to Australia from Iran.
"I am devastated that such a caring, loving, sweet and sensitive friend has been lost," he said."
'An act of God'
The survival of Kieran Low and Ebony Goodchild has been hailed as a miracle.
Assistant Police Commissioner Brian Codd, who has viewed CCTV footage of the shocking Dreamworld tragedy, said it was "the providence of God" that saved the two children.
Kieran, 10, and Ebony, 13, were thrown from the doomed raft when it collided with another and flipped on Tuesday.
Kieran's mum Cindy Low and Ebony's mum Kate Goodchild were killed, along with Ms Goodchild's brother Luke Dorsett and his partner.
"From what I've seen, it's almost a miracle that anybody came out of that," Mr Codd said. "If we're going to be thankful for anything, I'm thankful for that."
But he said the children would have a very tough time ahead of them after they witnessed the death of their mothers.
"(It has been) absolutely traumatic for these children, and it will continue to be," Mr Codd said, adding that the tragedy had a "deep and emotional effect on a lot of people".
He confirmed the ride would remain a crime scene for several days. "We owe it to the deceased and their families, we owe it to the community of Queensland, to get to the bottom of what caused this," Mr Codd said.
"If and where there is criminal aspects, including negligence, which warrants being pursued we will do that."