California officials say that sparks from a power tool used to clear brush was responsible for the Jesusita wildfires in Santa Barbara County that have destroyed or damaged dozens of homes and outbuildings and forced thousands to evacuate from their homes. (The map shows evacuation areas as of Sunday, May 10.)

Authorities declined to comment about the specific kind of implement that might have been at fault, according to this ABC News report. But "any time you use a power tool, there's always a possibility, especially if the conditions are right," a California Department of Forestry and Fire Protection official said.

Our experts agree, noting that carbon buildup near the exhaust port of gasoline engines can result in small pieces breaking loose, catching fire and being ejected as sparks. "But that's a very rare occurrence because most string trimmers, lawn mowers, and other power tools have a spark-arresting screen that prevent sparks from coming out," says our power-equipment guru Peter Sawchuk. "This could have been a case where someone was using an older model power tool. Or they could have pulled the spark arrestor out—even though it's a lot of work to remove one, and it doesn't improve performance in any way."

California Governor Arnold Schwarzenegger had declared May 2-9 Wildfire Awareness Week, and county officials had recently sent out notices requiring residents to clear brush around their homes by June 1 to reduce the risk of wildfires. Officials are still investigating the cause of the fires.—Gian Trotta | e-mail | Twitter

Essential information: Visit our Storm & Emergency Guide for information on dealing with wildfires. Our lawn-and-yard hub features buying guides and instructional videos on how to choose and safely use a wide array lawn and garden equipment.