With workers back on the job, Co-op refinery officials in Regina are trying to find out what caused a fire last night.
About 350 employees were evacuated Tuesday night when fire broke out in a pump house used to distribute crude to production areas.
However, the fire was extinguished and contracted workers were sent home.
Workers were back on the site, on the northeast edge of the city, this morning.
The fire was in a small area and the impact on production is minimal, the Co-op's vice-president of corporate affairs Vic Huard said.
The Regina fire department helped fight the blaze, and the refinery closed down valves to cut off the crude supply to the area.
The fire continued to burn for a while as the remaining fuel in the pump house was used up. No one was hurt.