Radio host Simon Barnett pulled an injured woman from the wreckage of a car which crashed in front of him and his family, cutting his hands on shattered glass as he did so.
Barnett witnessed the two-car collision while travelling with his two eldest daughters and their boyfriends on State Highway 5. He didn't say when the crash happened.
They were on their way to Taupo to meet Barnett's wife Jodi whose sister had died, aged 37, so were already feeling "morose", he said on his More FM show, Si & Gary.
About 20 minutes north of the town, while driving behind a Hyundai iMax, , a silver car in front of both vehicles pulled to the left of the road and for "no apparent reason" did a U-turn, Barnett said.
"I see it, but I'm not registering it. Well, I'm registering it now because I had to tell the police.
"I just look at it and it's a moment of sheer, blind, unadulterated panic because I go 'there is no way [the Hyundai] can avoid the silver car. There's just no way.'
"And sure enough, it just hits the vehicle, full on, straight into the side of it. And the sound is ghastly.
"Anybody who has been in an accident will know that sound. It's horrific.
"I just screamed. My kids told me I just went 'Oh no, oh no, oh no' and then boom."
Barnett said he was convinced someone would have been killed.
"I pull the car over and my heart is in my mouth," he said.
He heard the "piercing sound" of the iMax van's horn, which was stuck on, he said.
Shattered glass was everywhere, the cars were steaming and air bags had been deployed.
"I'm in panic mode, thinking 'What the heck do I do?' And then I hear screaming. And I'm like 'Oh no'. And the first thing I see is two children's car seats in the back of the vehicle that's been hit. I race to the car and there's kids crying. The driver that did the U-turn is a female and screaming 'I'm stuck, I'm stuck'."
Barnett said he immediately jumped into her vehicle, fearing it would burst into flames, and tried to pull off her seatbelt.
"I jump in to the car, and I cut my fingers on the glass. With all the strength I can muster - it's amazing what you think you can do that you can't - I pull the seatbelt."
But there was "no way this thing is coming off".
Traffic was starting to build and Barnett managed to get a knife from another driver in a campervan that had pulled over.
"I ran back to the vehicle, jump in the car and cut through the seatbelt, released the woman from her vehicle.
"Her kids are beside themselves. They will be about five and two if that. The poor woman kept saying, 'I'm sorry, I'm sorry, I'm sorry'."
Barnett described the smell of burning coming from the car was "palpable".
"She was screaming, I just thought 'I've got to get her out'."
Police told him it was a miracle no one was killed. Barnett didn't say what injuries the victims suffered.
He advised drivers to keep a knife in the glove box of the car in case of emergencies.
Barnett said his wife's sister had died a couple of days ago but did not say why. He said it was "dreadfully sad, just a ghastly situation. Thirty-seven years old, three beautiful children but I won't go there."
Barnett is married with four daughters.
