PITTSFIELD, Mass. — Authorities are offering a reward up to $5,000 for information leading to the person or persons who started a fire late Wednesday morning on Linden Street.

The vacant four-family structure at 213 Linden St. incurred what fire officials said was "moderate damage" to the first floor and basement.

Firefighters responded to the scene at 11:49 a.m. after a passerby noted smoke coming from the building. Upon arrival, they found heavy smoke throughout the building and flames in the basement extending to the first floor.

The call went to two alarms and all on-duty personnel were called to the scene; off-duty firefighters were called in to man the stations.

It took about 45 minutes to bring the fire under control. Five engines and a ladder truck responded to the scene and Deputy Fire Chief Mark Cancilla was the officer in charge.

No civilians were injured but one firefighter incurred a muscle strain.

The state fire marshal's office and city fire and police investigators ruled the cause of the fire as arson. Anyone with information about the fire should call 1-800-682-9229.