RCMP say two oil batteries at the Black Pearl Battery Plant west of Slave Lake ignited, and the tops of the tanks exploded Tuesday morning.
Police say each tank at the plant about 20 kilometres south of Canyon Creek contained 10,000 litres of crude oil.
Lesser Slave Regional Fire Department, Emergency Medical Services, Slave Lake RCMP and Municipal District Peace Officers responded.
Mounties say the fires were extinguished and all oil lines were diverted to ensure there were no further issues.
The cause of the fire is unknown.