A brush fire in the San Gabriel Mountains is burning out of control Sunday, destroying three structures and forcing the evacuation of 3,400 residents. The fire has already charred 3,500 acres of timber. Firefighters hope to stop the blaze in its tracks southeast of Wrightwood, a community of about 1,000 homes. More than 500 firefighters are battling the blaze, which was only 10 percent contained as of Sunday morning. The cause of the fire, which started Saturday afternoon, is unknown. California Governor Arnold Schwarzenegger has declared a state of emergency.