Local resident Brian Leathem said it seemed the fire engine had swerved to try to avoid the blue sedan, then struck the light pole, which toppled on to another car. "Another fire truck came through pretty quickly and went past the scene and just carried on to the original call-out," Leathem said.
"The fire engine only hit one car. It swerved to avoid it and it's knocked over a light pole which hit the back of another car."
Another local resident said he heard the crash, went out to assist, but firefighters from the damaged truck had told him they had the situation under control.
Ambulance Northern Communications team leader Norm Ngatai confirmed one person had serious injuries.
Three others, including "a young child" had been moderately injured. Ngatai said they were all taken to Middlemore Hospital.
Richard Toomey, Fire Service assistant area commander for Auckland, confirmed five volunteers were in the truck at the time of the crash.
He said the appliance had sirens and lights going as it was travelling along the 70km/h road, and an investigation would determine the speed of the fire engine.
"There was heaps of warning," he said. "The lights were on, the sirens were on. Everyone in the neighbourhood knew it was coming."
Toomey said the fire appliance was "severely damaged".
- Additional reporting by Jamie Small