A fire that broke out Friday morning at 10 Laurel Terrace in Somerville has been classified as the fourth set by arsonists this summer, said Mayor Joseph Curtatone.
Since June 27, there have been four confirmed arson cases in Somerville and five others that remain under investigation.
Today's blaze broke out at 6:40 a.m., officials said. The homeowner had seen smoke coming into her kitchen from the porch, and she extinguished most of the fire herself. Firefighters finished extinguishing it by 6:45 a.m., said Somerville Fire Department Lieutenant Derek Nolan.
A reward offered by the City of Somerville for any information regarding the ongoing case has been doubled from $10,000 to up to $20,000.
The reward could rise to $25,000 because the Arson Watch Reward Program is offering up to an additional $5,000 for any information leading to the arrest of any person involved in setting these fires.
"This has been a relentless investigation," said Somerville Police Chief Thomas Pasquarello. "We've devoted every resource possible including support that comes from our state and federal departments. No expense will be missing as far as what is required to bring the people responsible to justice in this investigation."
Pasquerello added that in some of these cases, entry was gained through unlocked doors. Other arsons or suspicious fires were started on the exterior of the homes.