Australia Dreamworld: Who were the victims?

(L-R) Kate Goodchild and Luke Dorsett were siblings, while Roozbeh Araghi was Mr Dorsett's partner. Cindy Low was on the ride with her 10-year-old son, who survived

Emotional tributes have been flowing in for the two men and two women killed on Tuesday at the Dreamworld theme park on Australia's Gold Coast.

Six people were aboard a raft on the Thunder River Rapids ride when it flipped after a collision with another raft.

Police said it was "almost a miracle" that a boy and a girl who were on the raft survived.

Friends and colleagues of those who died have been speaking out.

Kate Goodchild: 'Kind, loving'

Kate Goodchild, 32, was on a family holiday to attend a wedding, and decided to extend their trip to go the Gold Coast theme park.

She was a public servant in Canberra and had two daughters with her husband Dave, a 12-year-old girl and an eight-month-old baby.

She was travelling on the ride with her 12-year-old, who survived the collision, and with her brother Luke Dorsett and his partner Roozbeh Araghi, both of whom died.

Ms Goodchild's mother, Kim Dorsett, having lost a son and a daughter, said her family has been "wiped out".

"They really were just wonderful people - that would be the best way to describe them. They were kind, loving souls that would honestly do anything for anyone," she told News Corp Australia.

"I have two granddaughters ... and it truly breaks my heart to know that my eight-month-old is never going to get to know her mum."

Luke Dorsett: 'Greatly missed'

Luke Dorsett, 35, and his partner Roozbeh Araghi, were known for winning a high-profile legal battle with Canberra's local government over stamp duty in 2014.

Mr Dorsett and his sister both worked for the Department of Human Services.

"Kate and Luke were well-liked and respected by their colleagues and will be greatly missed," a department spokeswoman said in a statement.

Radio presenter Patricia Karvelas praised Mr Araghi and Mr Dorsett as loyal friends.

"They never missed one of my girls' birthdays. They never forgot to check in," she said. "Words fail me."

A friend said both men were amazing.

"Canberra is a very small gay community, everyone knew them or knows someone who knew them," Douglas Robinson said on Facebook.

Roozbeh Araghi: 'Loving, sweet'

It is understood that Mr Araghi, 38, was originally from Sydney where he studied history and edited the student newspaper, Honi Soit.

He worked for the Australian Bureau of Statistics, which in a statement described him as a hardworking member of its communications team "who brought joy and fun to the workplace".

Australian Senator Sam Dastyari said he grew up with Mr Araghi.

"I'm devastated that such a caring, loving, sweet and sensitive friend has been lost," Mr Dastyari wrote on Twitter.

"I'm angry that this could happen at a venue like Dreamworld."

Mr Araghi's family found out about his death from a TV news report.

"My second son found out accidentally on the news," said Mr Araghi's father, Behrooz.

"We've lost one son," he added, "The mother of my son's partner lost two [children]."

Cindy Low: 'Lovely, fantastic'

Cindy Low, 42, originally from New Zealand, lived in Sydney with her husband Matthew and their 10-year-old son and six-year-old daughter.

She was on a holiday to the Gold Coast with her family and some other friends, according to media reports.

Whilst queuing for the ride, she decided to separate from her husband and daughter, choosing instead to travel in a separate raft with her son and four strangers.

The decision proved fateful to her, though her son miraculously survived.

Her husband and her daughter who were in the other raft, were both unharmed but extremely distressed.

"She just kept screaming 'Where's Mummy? Where's Mummy?' eyewitness Claire Wooley said of the young girl moments after the accident.

Ms Low's father-in-law, Bruce, described her as a "lovely, fantastic person" and said her husband was "really struggling to come to terms with her death".