'It was bad' - witness speaks out about State Highway 5 crash

For Wendy Nathan, driving a road she's driven countless times turned into a life-changing event on Wednesday.

Travelling behind the truck involved in Wednesday's State Highway 5 crash, the first thing Nathan saw was smoke from the tyres.

Driving past, she saw it. A rental car squished against the truck.

"I stopped up the road because my daughter was in the car and ran to the site."

A qualified ICU doctor driving past also pulled over.

Approaching the wreckage, the pair initially saw three people in the car.

Nathan, who used her profession as a mechanic to see if it was safe to approach, said the car was "half the size it should have been".

Speaking to the Rotorua Daily Post, her voice wavered as she recounted what she saw.

"It was so bad."

Fuelled by adrenaline, Nathan said she and the doctor were trying to find a way to free the victims when they noticed a fourth person in the car.

With pliers from the truck, the women cut the seat belt of the passenger seat, which held the only conscious victim.

Following the doctor's instructions, Nathan got into the car where she could reach the driver, applying pressure to a gash on his head and holding his suspected broken jaw so he could breathe.

Two are critical and two stable following a truck and car collision on SH5 North of Rotorua. Photo / Ben Fraser

"I just listened to the doctor. How to hold him, how to keep him breathing ... I was her tool."

When fire crews arrived they prepared to cut free the trapped occupants.

"I was holding him together before the roof came up.

"I had a prayer in the car, and when I was finished he opened his eyes and then went back out.

"I don't know how to put it into words ... but he was strong."

When the roof came off, the paramedic prepared Nathan.

"He said, 'we're going to do this slowly and one hand at a time.' "

Panic set in as Nathan worried that moving would cause harm, but the paramedic kept her calm.

They carefully swapped hands on the head wound. Then the jaw.

"The first thing I did when I got out the car was go to the truck driver and give him a hug."

Despite the shock, she was thankful that the doctor, a nurse who also stopped and she were there.

"The way I see it, I was placed there for a reason."

Nathan said all emergency officials at the scene and Victim Support had been amazing.

"It wasn't until I got home it hit me."

She threw her pants, shirt and shoes away.

"I don't want to wear those clothes again."

Nathan was in a serious crash 25 years ago when she was 15.

"It just took me back to that moment I was stuck in the car."

She contacted Victim Support about meeting the family and visiting the man.

"I just want to give them a hug and let them know I tried," Nathan said.

Two of the victims remain in critical condition in the Waikato Intensive Care Unit.

The two who were taken to Rotorua Hospital are stable.

The police investigation is ongoing.