A fire that started in a storage room of a men's prison in Maple Ridge Saturday night remains under investigation.
Authorities have yet to determine what caused the fire, which began around 10 p.m. inside the Fraser Regional Correctional Centre on 256th Street.
The fire was confined to the storage area and did not spread.
Maple Ridge assistant fire chief Timo Juurakko said the fire activated the prison's sprinkler system, which quickly doused the flames.
When firefighters arrived, they checked the area to make sure the fire was completely extinguished.
A spokesperson for the Ministry of Justice said no one was seriously hurt or injured in the fire, but four staff were treated on site for smoke inhalation.
The unit where the fire occurred was back in operation on Monday.