Warehouse fire follow

Smoke continues to drift from a former Canadian Tire warehouse in Saskatoon. Since the fire began Friday, firefighters have had to return several times each day to extinguish hot spots. (CBC)

Fire investigators say it could be weeks before they know what sparked this weekend's warehouse fire in Saskatoon.

Smoke began pouring out of the Canadian Tire warehouse Friday afternoon. It took firefighters 19 hours to get the flames under control.

"It must have been going for a while because when the crews got there and they opened the doors, I just heard the term 'blast furnace'," said assistant fire chief Bill Coffin.

Warehouse contents unclear

Burning oil and tires were among a variety of substances fuelling the fire, sending what fire crews described as "toxic smoke" into the air. At one point an oxygen tank exploded.

Coffin said firefighters' efforts were initially hampered by heavy drywall used in the warehouse's construction, and "very few" access doors. Fire crews ended up bringing in a big excavating machine with a scoop on the front to tear apart the eastern side of the building, so they could attack the flames directly.

Canadian Tire warehouse fire in Sutherland

Crews responding to the fire Friday likened it to "a blast furnace", according to Saskatoon assistant fire chief Bill Coffin. (CBC)

Officials at Canadian Tire have not yet shared details with fire investigators about other items stored in the warehouse. There is no word on how much damage the fire caused.

Hot spots continue to flare

"The crews have had to go back and do spot fires a couple times a day, once or twice at night," said Coffin.

"We're trying to get a backhoe in or something in there so we can start moving some of this material and really get into the deep seat of the hot spots."

Coffin said the challenge is to do that without destroying evidence fire investigators need.