An estimated 1.5 million more people in California are set to lose power on Tuesday as a utility firm tries to stop damaged cables triggering wildfires.
Pacific Gas & Electric (PG&E) already faces an investigation by regulators after cutting supplies to 970,000 homes and businesses.
It announced that another 650,000 properties would face precautionary shut-offs on Tuesday amid high winds.
Wildfires fanned by the strong winds are raging in two parts of the state.
Thousands of residents near the wealthy Brentwood neighbourhood of Los Angeles have been told to evacuate because of a wildfire that began early on Monday.
Celebrities including the actor-turned-politician Arnold Schwarzenegger and basketball star LeBron James are among those who have fled the fast-moving Getty Fire, which started near the Getty Center arts complex.
Further north in Sonoma County, a larger fire has forced 180,000 people from their homes.
California's governor has declared a state-wide emergency.
On Monday regulators announced a formal inquiry into whether energy utilities broke rules by pre-emptively cutting power to an estimated 2.5 million people as wildfire risks soared.
They did not name any utilities but analysts said PG&E was responsible for the bulk of the "public safety power shut-offs".
BBC
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