He said the trio were inspecting a vat used to mix common industrial solvents when one worker became overcome by fumes.
“Someone went in first and then realised they were in trouble and that’s why the second person got in there to help get them out and they got into trouble as well.
“Another worker - there were three of them - called 111.”
Scott, who watched on as firefighters worked to save the pair, said the trio were now recovering at home.
“They’re all traumatised because, as you can understand, it was harrowing.”
He said the workers would be offered counselling, describing it as “a really traumatic event”.
Scott praised the emergency services for their swift response, and lifesaving actions.
“I was right in there. It was amazing how professional and fast the emergency services were, it was really quite impressive.”
He said the company would be investigating the incident.
WorkSafe had also been notified and was making initial inquiries.
Scott said the piece of equipment where the pair got into trouble was a vat with a manhole.
“It’s a mixing tank that’s normally inaccessible. The solvents are commonly used industrial solvents including toluene and ethanol but of course with dangerous vapours.
“I don’t want to get ahead of any WorkSafe inquiry but obviously those aren’t designed to be accessed so that’s where our investigation will get into.”
He said when the vats were accessed there was a procedure to vent it “so that’s where our inquiry will come in when everyone’s back”.
The factory was purpose-built for hazardous goods with vapour detection units and ventilation for the surrounding area.
“It has a vapour detector that if the vapours are detected over a certain threshold then factory shuts down.
“That’s outside the vat and not inside the vat,” he said.
A Fire and Emergency spokesperson said the three firefighters who were admitted for observation were discharged from hospital yesterday afternoon.
Yesterday Tāmaki Makaurau on-call commander Brad Mosby told the Herald the agency was “wrapping support around our firefighters in hospital”.
“[It was] an incredible effort by firefighters on scene to perform these rescues,” Mosby said.
He said the crews were wearing breathing apparatus but the two firefighters had been admitted to hospital as a precaution.