BANGOR, Maine — The Bangor fire and police departments and the state fire marshal’s office are investigating a fire of undetermined origin Saturday evening that damaged a vacant house on Center Street.

Firefighters initially were called to the area shortly after 6 p.m., when a woman who lives on Center Street Avenue reported what to her smelled like burning plastic, Assistant Chief Dennis Nadeau of the Bangor Fire Department said Sunday morning.

Although an initial investigation turned up a man burning wood in his grill, firefighters soon saw smoke coming from a single-story house at 69 Center St., Nadeau said.

Once they entered that building, crews found fire burning in a pile of clothing and other textiles, and they extinguished it. He said that the fire had just started to extend into the wooden beams and floor stringers when it was discovered.

The house was vacant at the time, he said. It had been placarded by the city on Oct. 4 because it was not considered habitable because of a lack of water service. It was not immediately clear who owns the house.