A passenger on a runaway bus says there were chaotic scenes seconds before the crash that claimed a life on Ōhakune Mountain Road on Saturday.
One young female passenger - believed to be an 11-year-old girl - is dead and four people are in hospital in a stable condition.
Aleisha Cope and her partner had taken the bus down Ōhakune Mountain Road from the Tūroa skifield as it was too icy for their car.
Ms Cope said five or ten minutes down the road there was a loud noise and other passengers started asking the driver if the brakes had failed, as the bus swerved all over the road before crashing.
"The driver was in shock and wasn't really saying anything ... trying to keep the vehicle on the road and was swerving to keep it straight on the road.
The bus, understood to be a 1994 import, ran into a few banks and everything happened really fast, she said.
"Someone said if you've got ski helmets or board helmets chuck them on and rushed all the people that were sitting in the front, to the back, especially the children, there were a lot of children at the front.
People put themselves in the recovery position, panicking and unsure what to do.
"It was a nightmare and people were screaming and I think people were praying, people were crying."
One man opened the back emergency exit and jumped out of the moving bus, she said.
"That was terrifying, seeing someone just jump out of the bus while we were just speeding down that hill."
Coming to a bridge, with a corner in the road she thought the bus would go over the side of the bridge.
"I thought, we're going to go straight through and we're going to die."
Just making it around the corner and over the bridge, the bus rolled and crashed.
Ms Cope's partner helped to drag her out of the main windscreen of the bus which had smashed.
"Everyone was just trying to get out, if they could move."
She's now in a lot of physical pain, needing help to move around.
"Emotionally I'm very drained and we've had a lot of tears today and our hearts are just aching for the family that lost their little one and it's just been a traumatic experience that no one should ever have to go through."
At the crash site, helicopters were called in to assist and a number of passengers were taken to the ambulance station in Ōhakune for assessment.
"We had up to 30 passengers scattered and quite a chaotic scene," St John Manawatu district operations manager Steve Yanko said.
A senior St John manager happened to be holidaying in the area and was drafted in to manage a second triage centre at the Ōhakune St John station.
He said this is quite normal practice.
"They're in the warm, they're away from the scene where a whole lot of emotion is connected with what's occurred so we were able to get them away from that and make good decisions about their care."
The skifield was closed yesterday, but is open again this morning following a karakia from local iwi which was attended by skifield staff.
"It was a pretty challenging thing to turn up to - a mass casualty site - and a lot of our front-line crew responded to that yesterday so it's important that we take the time to work through that," said Ruapehu Alpine Lifts CEO Ross Copland.
A bus service is running - but another Mitsubishi Fuso bus, like the one in the crash, has been taken off the road until an investigation is done.