The cause of a structure fire south of Libby in late evening Jan. 7 remains under investigation.

Crews responded to the blaze along Cherry Creek Bluff Road about 8:05 p.m., said Assistant Fire Chief Steve Lauer of the Libby Volunteer Fire Department. A property owner alerted authorities to the fire with a 911 call, he said.

About 23 firefighters worked the scene, joined by two engines, three water tenders and a command vehicle, Lauer said. Crews had the blaze under control in about three hours, leaving the scene shortly before midnight.

Lauer described the building as akin to a pole barn, with metal siding and a metal roof structure. Roughly 50 feet by 60 feet in size, it was relatively newly built, he said.

To attack the fire, crews used a two-and-a-half inch hose, which speaks to the scope of the blaze, Lauer said. Additionally, the roof caved in, leaving firefighters to force their way in by cutting holes in the exterior walls.

“It’s just a challenge getting in there,” Lauer said. “You just got to keep working at it.”

Unconfirmed reports of blasts went up on local Facebook pages during the fire. Lauer said the structure housed a shop and storage area. It held compressed cylinders, tires and flammable liquids, he said. But firefighters were able to save the building’s main propane tank from the blaze.

No injuries were incurred during the fire, Lauer said. He estimated damages at around $500,000. That price tag includes items inside the building, like a vintage automobile, tools and equipment.

Lauer said a fire investigator dispatched by the property owner’s insurance company would head the inquiry into the blaze’s cause.