Investigators are still trying to figure out what caused a barn fire that killed 3,500 piglets near Lanigan, Sask., this week.

The fire that broke out late Monday afternoon destroyed a barn filled with pigs between three and 10 months of age.

Casey Smit, vice-president of production with OlySky, said an alarm alerted a manager who found smoke in one of the barn's rooms.

Following the procedure to prevent the fire from spreading, he closed the door and called 911.

But by the time fire crews got to the farm, about 30 kilometres northwest of Lanigan, the fire had taken hold, and they could do nothing to rescue the piglets, Smit said.

"The issue is pigs don't move ... not like you just sort of herd them out," he said. "It's quite an ordeal and the policy is if there is smoke in a room you're not to enter a room because that's a risk."

Smit said it's likely the smoke killed the pigs.

It would be premature to speculate on the cause, he said.    

"There are fans in there that manage the ventilation, there are heating systems in there and of course there are lighting systems in there," Smit said. "We have a maintenance team that regularly looks after all the equipment and maintains it."

No staff were hurt, but the building was destroyed. An estimate of the damage wasn't available.

Olysky barn fire near Lanigan

A spokesman for the company the owns the barn said it's likely the pigs were killed by smoke. (RCMP)