Traffic was backed up on Auckland's northwestern motorway after a van hit a barrier, blocking a lane.
The incident occurred between the Lincoln Rd and Royal Rd off ramps on SH16 shortly before 6pm but has since been cleared.
Two people have been seriously injured in the crash and seven people have minor injuries, a police spokeswoman said.
A white van was towed from the scene.
Traffic is now moving again but earlier the stretch of motorway resembled a carpark as traffic was at a complete standstill for some time.
Some people had stepped out of their vehicles and were sitting on car bonnets. Others near the Royal Rd onramp were standing on top of their vehicles trying to see what was causing the delay up ahead.
Andrea Binning was two cars behind the white van when she saw it "spin around in a 360" and hit the motorway barrier.
After pulling over to check everyone was alright, Binning was told the driver lost control because a tyre had blown out while they were driving.
Eight passengers had been in the car, a family heading home from the beach, she said.
"It would be fair to say they were shaken up, but they were all thankfully ok considering there were that many people in the van and they had a pretty big stop against the barrier."
Binning helped out until emergency services said she could go, by which time traffic was 'backed up a very long way' behind the crash scene.
She had seen smoke but no fire coming from the van.
The van was on fire for a time, however no one was in the car when it was on fire, a police spokeswoman said.
The road was completely blocked eastbound toward the city.
Traffic started moving again shortly before 6.30pm.
People - a number of adults - who appeared to be involved in the accident or connected to the white van on the tow truck were helped across to the side of the road by authorities.