Relatives of some of the people killed at a theme park when their ride malfunctioned are pleading for answers into their loved ones' deaths.

Shayne Goodchild is the father of two of the four adults killed earlier this week at Dreamworld on Queensland state's Gold Coast. On Friday, he read an emotional statement on behalf of the families of the victims, who died when their raft overturned on the Thunder River Rapids ride on Tuesday.

Goodchild said the families want to know what went wrong with the 30-year-old Thunder River Rapids ride and why their loved ones were killed in such horrific circumstances.

Dreamworld will remain closed as a crime scene at least until Monday as police try and piece together what went wrong with the ride.