Gold Coast theme park Dreamworld will reopen Friday as police warn the investigation into the gruesome deaths of four people on an amusement ride will be long and complex.

The park was closed “indefinitely” after Tuesday’s incident, but on Wednesday evening Dreamworld confirmed a memorial day would be held from 11am on Friday, with only smaller rides, animal attractions and the water park open.

All entry proceeds will go to the Australian Red Cross and before the opening, a private ceremony will be held for staff, friends and emergency services involved in the response to the incident.

Kate Goodchild, her brother Luke Dorsett and his partner Roozbeh Araghi were killed alongside 42-year-old Cindy Low while riding the Thunder River Rapids ride at the Gold Coast theme park.

Ms Low’s 10-year-old son and Ms Goodchild’s 12-year-old daughter were thrown from the boat in the accident and suffered only minor injuries.

Dreamworld chief executive Craig Davidson has promised to help the two young survivors.

“These children will have our full support into the future,” he said.

Authorities said the accident occurred when two rafts hit one another at the end of the ride, tipping one backwards. An empty raft reportedly became stuck, with the moving raft holding the victims hitting it.

In a statement on Wednesday evening, Dreamworld said the Thunder River Rapids ride successfully passed an annual inspection or “external audit” on September 29.

“The safety audit was conducted by a specialist external engineering firm,” the statement said.

“Details of this external audit will be provided to the coroner and workplace safety investigators.”

One of the rafts involved in the incident is taken away to be examined. Photo: Network Ten

Earlier in the day, Detective Inspector Mark Thompson said police had collected more than 40 witness statements, but still sought more.

“[I would ask] anyone who was present at Dreamworld and has any information, eyewitness accounts of this incident we’re investigating, or any photos or footage that they may have taken on mobile phones, to contact Crime Stoppers in order to assist us with our inquiries,” he said.

“Police are also specifically looking for anyone who may have taken a ride on the Wild River Rapids ride at Dreamworld yesterday [Tuesday] to particularly contact police.”

Family, friends grieve

The family of Ms Low, a partner and mother, said they were devastated and traumatised by her death and have asked for privacy.

Tributes for Ms Goodchild, Mr Dorsett and Mr Araghi have emerged from federal government departments in Canberra. Ms Goodchild and Mr Dorsett worked for the Department of Human Services and Mr Araghi with the Australian Bureau of Statistics.

Kate Goodchild was killed on the ride. Photo: Facebook.

An ABS statement read: “The ABS is devastated by the tragic loss of Roozi Araghi, one of our dedicated, professional hard-working team members, who was very popular and well-regarded.”

The mother of Ms Goodchild and Mr Dorsett told News Corp of her anguish that “my family have been completely wiped out“.

Federal senator Sam Dastyari and broadcaster Patricia Karvelas are two of the many friends who have paid tribute to Mr Araghi and Mr Dorsett.

Senator Dastyari said he was raised alongside ‘Roozi’ Araghi, whose father helped paved the way for his own move from Iran to Australia.

“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.”

Safety questions

It also emeged Wednesday that Dreamworld owner Ardent Leisure sought to block the release of 143 pages of critical information relating to ride safety and inspections earlier this year, including a report the Thunder River Rapids ride was “not fit for service”.

The Queensland Information Commissioner in July ordered Dreamworld to release the critical documents that detailed years of incident reports, notes from inspections and complaints to the Australian Workers’ Union (AWU).

The order came after the AWU, which represents workers at the park, had a request for internal information in order to carry out regulatory activities refused.

Emergency services personnel at the scene of the accident at Dreamworld on Tuesday.

“Dreamworld broadly objected to disclosure of any documents in relation to the application,” the information commissioner’s judgment says.

The AWU was eventually forced to narrow its request to specifically include information on rides and plant machinery.

– with ABC