The fire at the Department of Conservation and Recreation building on Elm Street in New Salem Thursday night has been ruled accidental.
According to Department of Fire Services spokesperson Jennifer Mieth, the focus of the investigation is the woodstove, which is the area where the fire started.
Mieth said the electrical system cannot be completely ruled out though due to the extent of the damage.
Employees used the woodstove to heat the building after power was lost earlier in the day Thursday, Mieth said.
Someone passing by the building at 9:15 p.m. noticed the fire and reported it.
Mieth said the fire caused $500,000 in damage, and destroyed the building and several cars. No one was injured in the fire.