Kalispell authorities say someone burned a foam pole-vault mat on the Glacier High School track, causing $40,000 in damage.
School officials say Tuesday's fire destroyed the school's pole vault pits and damaged the pole vault standards, the rubber runway, a fence and the concrete surface.
Kalispell Fire Chief Dave Dedman tells the Flathead Beacon it's not clear whether the fire was set intentionally because most of the evidence was consumed by fire.
Glacier Activities director Mark Dennehy says investigators are analyzing video surveillance images and other leads.
A $1,000 reward is being offered for the arrest and conviction of whoever is responsible.