Investigators in Gravenhurst are trying to figure out what started a big fire this morning at a public works yard that caused almost $500,000 in damage.

Investigators say it may have started with a piece of equipment that's very important at this time of year, as they sift through the charred and heavily damaged service garage at the Gravenhurst public works yard.

Dan Bray arrived for work just after 6 a.m. today and discovered the fire.

“When I came into the yard I noticed flames coming out of the garage, and I called the fire department,” he says. “We checked the building to make sure nobody was in there.”

No one was in the garage when the fire broke out and fire crews were able to contain the flames within minutes. Three service bays and a sidewalk plow are destroyed. Early estimates have damaged pegged at almost $500,000.

“The three bays have been heavily damaged, the roof structure is not safe, the roof was made out of combustible wood and was heavily damaged,” says Fire Chief Larry Brassard.

Investigators are not considering the fire suspicious but the cause isn't known. The Ontario Fire Marshal's office is helping with the investigation and is focusing on the plow.

Jeff Tibby says it may be the cause.

“We are looking at (the sidewalk plow) as the area of origin because of the fire damage to it and the ignition sources that are in it – the electrical components, the battery.”

At this point investigators don't know what may have caused the plow to spark. 

In the meantime snow plows and salt trucks continued to come and go from the public works yard today. The town's director of infrastructure says the service garage was used to repair equipment and fleet vehicles. Geoff Carleton says this fire shouldn't have an impact on winter maintenance operations.

“We're operational as normal,” says  Carleton. “We're working with our providers to make sure there is no hindrance to the service we provide. We've reached out to our colleagues in Bracebridge if we need assistance.”

The fire marshal has also called in an engineer to help with the investigation and to specifically examine the sidewalk plow. It could take several weeks to determine what caused the fire.