The Kincade fire in Sonoma County kicked up Wednesday night, quickly growing from a blaze of a few hundred acres into an uncontained 10,000-acre (4,000-hectare) inferno, California fire and law enforcement officials said.
Mandatory evacuation orders were issued for the town of Geyserville, California, the county sheriff's office said.
High winds out of the north were driving the fire south as firefighters worked through the night to evacuate residents and protect structures.
"This fire is moving fast, please pay attention to evacuation orders," state Senator Mike McGuire said on his Twitter account.
The Kincade fire came amid official warnings that much of northern California and parts of the south were under imminent threat of fires into Friday because of blustery, dry weather.
Citing strong Santa Ana winds, San Diego County warned residents of potential power shutoffs for tens of thousands of customers to reduce the risk of accidental fires.
San Diego Gas & Electric notified 42,000 customers that power shutoffs were possible.
Several fires were burning in the Los Angeles area, and at least one fire near Pendleton, California in San Diego County.