Halton Police are investigating a suspected fatal overdose at a jail in Milton.
One inmate has died, five others are in life-threatening condition.
Officers and paramedics were called to Maplehurst Correctional Complex just before 6 p.m. Tuesday night and found the six inmates inside the same cell block.
"Police cannot comment at this time on the type of drug used, how it was used or how it came into the possession of the involved inmates," officers said in a news release. "Detectives with the 1 District Criminal Investigation Bureau have responded and are continuing to investigate in cooperation with the coroner and Maplehurst staff."
Maplehurst is a maximum/medium security facility with a capacity for 1,500 inmates.