The cause of Tuesday morning's fire was ruled undetermined, but the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives announced Wednesday that investigators found no accelerant or other evidence of a criminal act.
The early morning blaze destroyed the Bureau of Land Management's field office on Blue Mountain Road in Challis. An ATF team spent two days conducting interviews and analyzing debris from the fire, according to a Wednesday evening news release from the bureau.
The building, where 25 federal employees worked, is a total loss but no dollar estimate was available, officials said. No injuries were reported.
The BLM Challis Field Office manages 792,243 acres of public lands, mostly in Custer County. Already, ranchers who graze their cattle on those public lands are worried about the loss of valuable research data used for planning and range management.
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But BLM officials said Tuesday it was too early to determine the scope of the loss of documents and computer files.