PRINCE ALBERT, Sask. - One prisoner is dead and two others have been seriously injured in a fight involving at least 10 inmates at a federal prison in Saskatchewan.

The Correctional Service of Canada says the maximum-security unit at the penitentiary in Prince Albert has been locked down.

Spokesman Darcy Begrand says inmates who usually get along with each other were in the lunch area when seven prisoners turned on three others.

The two injured inmates are being treated in hospital.

Begrand says it's not clear what sparked the fight, if the inmates are gang members or whether weapons were used.

RCMP, the correctional service and the coroner are all investigating.