Smoke was pouring from the basement of a Fairmount Street home when firefighters responded Thursday night to a report of a fire there, but it took some digging to find the source of the fire.

The blaze was in the furnace, enclosed when an illegal basement apartment was built at the house at 25 Fairmount Ave., said Lt. Edward Williams of fire prevention.

Firefighters responded at 7:49 p.m. and cleared the scene at 11:08 p.m. after the American Red Cross responded to relocate the residents, he said.

Capt. Victor Parziale was scene commander.

Williams said the blaze caused an estimated $10,000 in damage in the two-family house that was being used as a three-family dwelling. The basement apartment was occupied by one person.

No injuries were reported. Power was cut to the building, and the Building Department was notified of the illegal apartment, Williams said