Firefighters from four Sonoma County communities battled a blaze in a large industrial building south of Cloverdale Sunday afternoon.

The fire started inside the Nu Forest Products facility at 280 Asti Road around 3:42 p.m. and proved challenging to fight because it spread into the walls and roof of the large, older structure, said Cloverdale Fire Battalion Chief Rick Blackmon.

The fire appears to have started in an area of the building leased to another company, Martinez Saw Shop, which sharpens industrial sized saw blades, Blackmon said. A fire investigator will have to determine the official cause, he said.

Because of the size and age of the building and wood products on site, the potential for a massive fire was significant, Blackmon said. Firefighters from Geyserville, Healdsburg and Windsor assisted Cloverdale.

The building's sprinkler system did a good job of keeping the fire in check until firefighters arrived. Their battle to contain the fire and chase down the flames in the walls and roof took nearly four hours, Blackmon said.