Authorities say a state-owned excavator doing routine maintenance somehow started a wildfire that destroyed eight homes in southern Colorado.

Pueblo County Sheriff Kirk Taylor announced Thursday that the operator of the Colorado Department of Transportation machinery was moving a stone Monday when he noticed a fire had ignited. The Pueblo Chieftain reports that the operator unsuccessfully tried to stamp it out with the earthmover's bucket before calling 911.

Taylor says it's not clear exactly how the machine started the fire - such as by creating a spark by scraping rocks or with its exhaust. He says the operator isn't a smoker.

State transportation chief Mike Brown said he agreed with the findings of the investigation into the fire, which grew to about 8 square miles and forced the evacuation of hundreds of people in the rural community of Beulah near Pueblo.

The state says it will give $5,000 stipends to those who lost everything in the fire.