Party-goers watched in horror as a vehicle spun out and clipped a man standing on the footpath, sending him somersaulting two metres into the air before landing in the middle of the road.
The 25-year-old man has had surgery and remains in a serious but stable condition in the high dependency unit at Waikato Hospital after being hit by a vehicle on Rosamond Terrace in Kawhia on Sunday morning.
The driver ran off after the crash but police have now spoken with him.
A witness told the Herald of the horror of watching the man flip two to three times in the air before landing flat on his back in the middle of the road just before 1am on Sunday.
A group of people - many of whom were experienced first aiders - rushed to help him while he "lay lifeless on the ground", the witness said.
The victim had been attending his girlfriend's birthday party and had been standing on the footpath trying to defuse a fight between about two groups of three people when he got hit, the witness said.
"What happened is the person who got hit, he wasn't fighting anyone, doing anything like that. He was just trying to peace-keep."
Earlier in the night there was an altercation between two people at the party, he said. The fight escalated on to the street when a group of young people arrived with a car which had been "hooning", he said.
One person hopped out of the car and started trying to fight people. His friend then hopped in a second car parked at the address and started trying to scare people by driving at them, the witness said.
"It was very scary."
He said the car seemed to be going at least 50km/h and appeared to be heading towards the group of people fighting on the road.
Everyone suddenly looked as the car's brakes made a loud screeching sound and the car spun out of control.
It hit the man, sending him flying about two metres into the air, and the car crashed into a small retaining wall at the front of the property.
He said the driver tried to leave in the car but it was wedged in the wall.
"He [the driver] just kept driving forward and when that didn't work he ran off."
A woman was in the passenger seat, but jumped out of the car after it crashed.
Two people who attended the party told the Herald they disagreed with comments made by another party-goer on social media that the car had been travelling at only 20km/h.
The victim was flown by rescue helicopter to Waikato Hospital and a group of people left at the same time by car to be by the injured man's side. Police took witness statements from them at the hospital.
Police said officers were continuing to make inquiries and no charges had been laid at this stage.