A fire that destroyed three homes under construction was the work of the eco-terrorist group Earth Liberation Front (search), officials said.
The fire broke out about 2 a.m. and was confined to the homes that were already on fire, said Susan Smith, a dispatcher with the city fire department. It took firefighters about an hour to knock down the flames, she said.
The fire occurred in the Torrey Santa Fe area in a north-central part of the city that is under development. Arson investigators were sent to the scene, Smith said.
The California Highway Patrol (search) on its Web site reported the blaze as an "Earth Liberation Front fire." The group is a loose association of militant environmentalists and previously has claimed responsibility for acts of arson and vandalism.
A banner was hung on a building near the fire, but no information was being immediately released on its content, said Officer Rich Vergara of the San Diego Police Department.
No damage estimate was immediately available and no injuries were reported.
The Earth Liberation Front took responsibility for a $50 million arson blaze in August that destroyed a five-story apartment building in San Diego that was under construction.
The FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives (search) have been investigating that incident as well as an arson and vandalism attack targeting Hummers and SUVs in Los Angeles County earlier this month.
FBI spokeswoman Jan Caldwell said early Friday that she had no information on the blaze.
A second blaze was reported at 3:52 a.m. and destroyed one home that was under construction, a fire dispatcher said. Firefighters had the blaze, which also scorched a patch of grass, under control in about half an hour. The fire, which broke out about three miles west of the original blaze, was under investigation, said fire dispatcher Kelly Refer.