A prisoner was killed and several people were injured during a riot at Saskatchewan Penitentiary on Wednesday.

Prison officials said three inmates were stabbed at some point during the riot in the Prince Albert prison's medium-security unit.

Jason Leonard Bird, 43, was pronounced dead after he was brought to hospital by paramedics.

Two other inmates were taken to hospital in serious condition.

James Bloomfield, regional president with the Union of Canadian Correctional Officers, said that in the days leading to the riot there had been concerns by inmates regarding the portion size of meals.

A confrontation began around 1 p.m. CST Wednesday, following lunch, when inmates would normally be heading back to their cells.

"However, the inmates, at that point, refused to lock up," said Bloomfield. The number of inmates refusing to lock up ranged from 185 to 200, he said.

Negotiators brought in

Guards in the medium-security unit have limited tools at their disposal, Bloomfield said.

"The tools we have on us are handcuffs. We have pepper spray. We have stab-resistant vests."

As the inmates refused to lock up in their cells, negotiators were brought in.

A prisoner has been killed at Saskatchewan Penitentiary in an incident that triggered a riot. (Thomas Porter/Canadian Press)

"The negotiators quickly realized that was not going to be fruitful, and the emergency response teams were called in."

While emergency teams were being called, Bloomfield said, the inmates began to riot.

"They smashed out all the lights, all the cameras, all the windows."

The inmates also set up barricades.

3 inmates found stabbed

Bloomfield said that as the emergency responders breached the barricades, it was discovered that three inmates had been stabbed. Those inmates were taken to hospital, but one — Bird — was pronounced dead.

Shots were fired by guards as they took control of the area, sending five to hospital. None of the injuries is considered life-threatening.

"In gaining control, they did fire shots down range," said Bloomfield. "That resulted in six inmates being hit with pellets. It's not a direct aim at an individual and fire at them; it's a different type of shot that we used in this to suppress the crowd and to hold them from charging."

The maximum-security unit was subsequently locked down at 3:30 p.m. as a precautionary measure.

The prison is now under control, says Correctional Service Canada, but visits are still suspended.

Police and the correctional service are investigating. Bloomfield said part of the investigation will be to determine when the inmates were stabbed and who is responsible.

Prison staff are assessing whether there are any other injuries and the extent of the damage. There will be a full review.

Bird was serving two years and seven months for breaking and entering and related offences.