PRINCE ALBERT, Sask. - A Correctional Service Canada report says a walkout by prisoners working in the kitchen could have been the catalyst for a riot at Saskatchewan Penitentiary that left one inmate dead and eight others in hospital.

The final report says a number of issues were already brewing at the medium-security prison in Prince Albert before violence erupted on Dec. 14, 2016.

The National Board of Investigation found work- and food-related concerns, ongoing negotiations between inmate representatives, kitchen staff and institutional management, plus changes in prison management contributed to prisoner discontent.

It also determined that the presence of an inmate with a history of inciting other prisoners to act out was a contributing factor.

The report says after the kitchen walkouts, other inmates refused to go to work and prisoners on some cell ranges refused to lock up, which escalated the riot.

Criminal and other charges were laid against several key inmates involved in the violence that lasted for about six hours and caused $3.5 million in damage before it was quelled by an emergency response team.