A fire in an air filtering system led to a smoky blaze Friday morning, Jan. 19, at snowplow maker Fisher Engineering.

Rockland Fire Chief Christopher Whytock said the smoke was so thick inside the manufacturing building that he could not see the other side of the building when he went in.

One employee from Fisher was checked for smoke inhalation, but declined to be taken to the hospital, the fire chief said.

The fire started when a spark — from a grinding machine being used near the large air-filter unit — got into the air-handling system. The chief said the filters are made of combustible material and the 6-by-12-foot unit caught on fire, spreading smoke through the building.

Camden, Rockport and North East Mobile Health responded to the fire scene, while crews and trucks from Thomaston and South Thomaston went to the Rockland fire station.

The call came in at about 9:30 a.m.

Firefighters were on the roof of the sprawling complex, checking to see if there was any spread of the fire into the duct work, but the chief said the fire did not spread.

Employees were evacuated to an adjacent parking area.