Mr Irwin, who was manning the Gold Coast parks communication hub on October 25, 2016 when he received the call, spoke at an inquest on Tuesday, looking into the deaths of Cindy Low, Kate Goodchild, her brother Luke Dorsett, and his partner, Roozi Araghi, at Southport Coroners Court.
He told the court he heard a panicked voice say, ‘I’ve got a raft in the conveyor’ then he looked at the CCTV footage and realised there was a serious problem, news.com.au reports.
By the time he made the Triple-Zero call to the ambulance, first aid responders told him at least one person was unconscious and ‘turning blue’.
Whilst making the call, Mr Irwin upgraded the emergency to a ‘222 emergency’- the park's most serious emergency code.
Mr Irwin said staff at the park acted swiftly.
‘Unfortunately, there was just nothing we could do when we got there,’ he told the inquest.
Four of the former employees who were first responders to the accident are now suing Dreamworld.
The group, which includes safety officers Shane Green, John Clark and Rebeca Ramsey and engineer Paul Burke, say they are 'psychologically damaged' from trying to help the four trapped victims.
In a statement to news.com.au, solicitor Tina Ibraheem, from Shine Lawyers, said the four first responders' ‘level of trauma is beyond anything I have ever seen’.
‘One of the hardest memories for our clients to forget is the screams of the victims’ family members who were right there wanting them to do more to save their loved ones. They so desperately wanted to do more, but the victims were gone,’ she said.
The four remain in ongoing counselling and at least three of them are expected to testify to the inquest at a later date.
The inquest continues.