CHALLIS, Idaho - The fire that destroyed the Challis office of the Bureau of Land Management this week.was not a criminal act, Bureau of Alcohol, Tobacco, Firearms and Explosives investigators have determined.

The ATF said Wednesday that the agency had completed its on-scene investigation into the cause and origin of the fire.

The cause was ruled undetermined with no evidence of any criminal act, the ATF said.

Although investigators can't conclusively determine the cause, they found no evidence of added accelerant.

The fire was reported early Tuesday morning, and the building that housed 25 employees is a total loss.

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No injuries were reported.

The ATF said the initial damage estimate is in the millions.