SAN FRANCISCO (AP) – California’s largest utility says the deadliest of last month’s wildfires may have been started by electrical equipment not owned or installed by Pacific Gas and Electric Co. The San Francisco Chronicle reports the utility says in a legal filing Thursday that a preliminary investigation suggests that a private power line may have started the blaze that killed 21 people and destroyed more than 4,400 homes in Sonoma County. PG&E did not name the third party but referenced a Napa County location where investigators have focused their work on the cause of the fire. The filing comes in response to several wildfire-related lawsuits against PG&E. It gives no supporting evidence other than referring to an electric incident report that the utility submitted to state regulators in the wake of the fires.