Kathleen Tahau was on her way to work when two cars collided at a busy set of traffic lights in Hamilton.
Nearby drivers, and a group of motorbike riders, rushed to help as smoke began to seep from one cars which had flipped.
The two-car crash happened at the intersection of Mill and Anglesea Sts at midday, bringing lunchtime traffic to a halt.
The front of a grey people-mover was badly damaged and a car could be seen flipped onto its side, surrounded by shattered debris.
The cars crashed on the corner of Anglesea and Mill St.
Traffic controls were in place at 12.30pm while Fire and Emergency Services attended the scene.
Everything seemed to slow down when the car crashed onto its side, Tahau said. Then she saw the smoke.
"It was scary, like is this actually happening?," Tahau said. "I thought is it going to blow up?
Three motorbike riders sprinted over to the flipped car and pulled a woman and her grown son from it.
The trio wrenched the boot open and pulled out a young man and a woman, who was dazed and bleeding.
"They were the heroes," Tahau said. "They had all their gear on and they just ran over and started going for it.
"They didn't muck around. Then other people started jumping out of their vehicles and coming over and helping."
A woman and a toddler were among those in the other car, a grey people-mover. The woman could be seen crying and hugging the toddler before being taken away by an ambulance.