Then the campervan and the car collided, Klenner said.
"The campervan rolled and I just slammed on the brakes."
Corbett said it all happened pretty quickly and the drivers of the cars in front rushed to the car.
"We don't see fatals very often, but accidents, we see all the time."
Klenner said a man was still alive inside the car when emergency services arrived on the scene.
"They were trying to get him out with the jaws of life, and then they just stopped, it was too late."
There were at least eight trucks parked up beside the cordon as they are unable to divert from the State Highway.
"It's hard to know that someone has died, and that someone has now lost a family member," said Klenner.
Rotorua Fire Brigade senior station officer Jim Prescott said the Mamaku Volunteer Fire Brigade responded first.
"When we arrived the campervan was on its side about 100m from the car.
"The passengers of the campervan had minor injuries but the driver of the car was seriously injured and died at the scene.
"Once it was established he was deceased the police had to undergo their investigation."
Prescott said they cut the car to free the body about 12.40pm.
"Most of us have been doing this for a long time and we have good support among our crew.
"You don't ever become hardened to these type of crashes, but we get each other through it."
The Serious Crash Unit has been notified and would investigate the cause of the crash.