Two male inmates are dead and another six are in hospital after a fire was started during a riot at a provincial prison north of Quebec City.

The riot at the Orsainville prison began at about 9:30 p.m. on Wednesday night.

Marc Lyrette, a spokesperson for Quebec's Ministry of Public Security, said 14 inmates were involved in the riot that took place in the prison's F-wing.

Another ministry spokesperson, Johanne Beausoleil, described the start of the riot as "an altercation involving somebody who was incarcerated, but we don't know what set it off."

"It's obviously a tragic and deplorable event," said Beausoleil, who noted that all inmates involved in the scuffle were awaiting the end of ongoing trials.

When the warden tried to intervene, some of the inmates set mattresses on fire.

Authorities ordered the inmates to evacuate the area, but eight of the inmates refused to comply, Lyrette said.

After the fire was extinguished, authorities found the bodies of Eric Adamson Yaouvi, 20, and Denis Ampleman, 45. Autopsies will be required to determine their cause of death.

The six other inmates were taken to hospital with various injuries, including smoke inhalation.

Lyrette said all of the inmates in hospital are expected to survive, and the fire caused only minor damage to the prison wing.

Four of the injured inmates have been returned to the prison. Two more were being treated for non-life threatening injuries.

No guards were injured.

Provincial police and prison officials are now investigating the incident. The wing where the riot and fire took place is presently sealed.

"They are being very tight-lipped about the nature of the investigation," said CTV Montreal's Derek Conlon, reporting outside the prison on Thursday afternoon.

Lyrette said inmates are allowed to smoke while outdoors at the Orsainville prison. That means that many inmates have routine access to lighters and matches.

It's not the first time that a riot has occurred at the Orsainville detention centre.

Another riot happened in February 2008, apparently triggered by a smoking ban at the facility.

With files from The Canadian Press