The porch fire that caused about $10,000 in damage in Somerville this morning has been declared arson, officials said.

The fire was reported at 6:40 a.m. on Laurel Terrace. The homeowner had seen smoke coming into her kitchen from the porch, and she extinguished most of the blaze herself. Firefighters finished extinguishing it by 6:45 a.m., said spokesman Derek Nolan.

Fire Chief Kevin Kelleher said the fire was “very suspicious,” after two fires in Somerville last week.

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On Aug. 28, around 5:30 a.m., a two-alarm fire broke out on Bromfield Road. Shortly after firefighters responded to that fire, another two-alarm blaze was reported about a mile away, on Summer Street. Both took about a half-hour to extinguish, officials said.

Four house fires have been deemed arson since, four have been ruled accidental, and five are still under investigation, all since June, the city said in a statement.

The reward offered for information leading to an arrest of any person involved with these fires has been doubled from $10,000 to $20,000. The Arson Watch Reward Program is also offering up to $5,000, the statement said.