All three prisoners who were in the back of a sheriff's van like the one pictured here were injured in the crash. (CBC)

An eyewitness to a recent crash of a sheriff's van in northern New Brunswick says the prisoners were bounced like "marbles in a can," raising questions about the way inmates are transported.

All three prisoners were injured, along with the two sheriff's officers who were accompanying them from the Dalhousie Regional Correctional Centre to court.

John Cranton was following the Chevrolet Astro van on Route 11 during a snow storm on April 23 when the vehicle suddenly spun around on the slippery overpass in Nash Creek and rolled at least four times.

"It just went into a big sweep," landing about 60 feet away from the highway and about 20 feet below highway level, he said.

Cranton stopped and ran to the scene to assist and found the most seriously injured of the three prisoners lying on the floor in the back of the van in a daze.

'It would be the same as putting a handful of marbles in a can and shaking it for all it was worth.' —John Cranton, witness

"He had blood coming out of one ear, blood coming out his nose, cuts all over his face and he was just kind of staring off into space," said Cranton.

"He was not hooked to anything. He had handcuffs on and shackles on his feet. He couldn't even... He just bounced around in there."

The other two prisoners were sitting on a bench, attached by their handcuffs to a metal screen at shoulder height in front of them, Cranton said.

"It would be the same as putting a handful of marbles in a can and shaking it for all it was worth," he said. "These guys were really beat up badly — the three of them. They really took a beating."

There did not appear to be a first aid kit in the van, but the two sheriff's officers did their best to assist the prisoners even though they were injured themselves, said Cranton.

All three prisoners were taken to hospital. Two were treated and released back into custody, while the third remains in hospital with what Department of Justice officials describe as "non-life threatening injuries."

"I'm not an advocate for criminals' rights, but I'll tell you what, like I really felt bad for those guys," said Cranton.

Department of Justice spokesman Dave MacLean says seatbelts are provided for prisoners, but they "may choose not to wear" them while being transported.

The two sheriff's officers suffered minor injuries.

There were eight other accidents in the area that day due to road conditions, the RCMP has said.