Firefighters responded at 3:30 a.m. Thursday to Merritt Bros. lumber mill, in Athol.

Ralph Kramer, deputy chief of Northern Lakes Fire District, said a fire started in a metal hopper where sawdust is collected before being dumped into a truck.

The hopper was not damaged. A truck trailer next to the hopper sustained slight damage, he said.

The mill is located west of Old U.S. Highway 95 and just south of Highway 54.

The cause of the fire has not been determined, Kramer said.

No injuries were reported.

Along with Northern Lakes, fire units from Timberlake fire district, Kootenai County Fire and Rescue, and the cities of Spirit Lake and Sagle responded, he said.