Thick, black smoke billowed from the machine shop at the Sparboe Farms facility south of Litchfield off of Highway 22, Thursday afternoon.
Litchfield firefighters were seen swinging their axes to break down garage doors on the east and west side of the machine shop to get inside to stop the flames.
Once inside, the culprit of the fire was discovered - a semi-tractor.
"The semi-tractor was on fire, (cause) unknown," Litchfield firefighter Glendon Caron on the scene said. "It sounds like it just got pulled there. (The driver) unhooked his trailer, pulled in and left."
By 4:15 p.m. the fire was under control and the fire departments and rescue squad were working to ventilate the building.
No one was in the machine shop during the fire and no one was injured, officials on the scene said.