FLAGSTAFF, Ariz. — Editor's note: The above video from July reports on the community coming together to support firefighters working to contain the Museum Fire.
The Museum Fire that charred more 1,900 acres of land and will cost the state about $12 million was sparked by a machine used to reduce the risk of wildfires, according to the U.S. Forest Service.
The fire began on July 21 and it was declared contained nearly a month later on August 15.
Forest Service investigators found the fire was likely started by an excavator hitting a rock during a forest thinning operation. The spark made a heat source that hung around until warm, dry and windy conditions moved in. This created a small fire which quickly spread and grew. Fire officials say hitting a rock isn't unusual in steep terrain during forest thinning operations.
Experts say deep forest fuels and roots can hold heat for a long period of time. They can burn and smolder underground for days, weeks and even months without any sign of a fire. And they surface when it warms up and it's windy.
The equipment passed inspections and there was no negligence, according to the Forest Service.
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“It’s unfortunate that the Museum Fire started as the result of ongoing restoration work designed to reduce the risk of uncharacteristic wildfire and improve forest health and resiliency—especially in the Flagstaff area where citizens joined together to invest resources to help fund the Flagstaff Watershed Protection Project,” said Coconino National Forest Supervisor Laura Jo West.
“Fortunately, some of the restoration work that had been completed previously in and around the wildfire area actually helped stop the fire from becoming larger and more destructive.”
Analysis shows 50 percent of the Museum fire burned at low severity while just 12 percent burned at high severity.
The Associated Press contributed to this article.