“He was hanging onto the door handle with both hands and trying to keep his feet off the road.”
Allan said the vehicle did not appear to slow as it approached a speed hump near a bridge before turning into the side street.
“The car was going at speed and when it turned left into Myers Rd, he was flung off.”
Allan said he pulled over shortly afterwards and looked in his rear-view mirror, where he believed he saw the man fall from the vehicle.
“I saw a shoe and some clothing on the road, so he must have lost his grip,” he said.
Allan said he drove back past Myers Rd 15 minutes later and saw police vehicles, an ambulance and a helicopter responding.
Hato Hone St John told the Herald they sent an ambulance and critical care unit to the scene at 7pm.
One patient was taken to Middlemore Hospital in a serious condition.
Police are carrying out inquiries into what happened and to find anyone else involved.
Cordons at the scene have since been removed.