PotashCorp. says there's no word on the cause of the blaze that broke out Tuesday at its Rocanville (ROH'-kahn-ville) mine, about 245 kilometres east of Regina.
Officials had said a large wooden cable spool started burning.
Spokesman Bill Cooper says it is likely to be days before the company knows for sure what sparked the fire.
Cooper says some air testing has been done to ensure that the mine is safe to enter.
It took about 10 hours to put out the fire and several more hours for rescue crews to determine that it was safe to bring the workers up.