A statewide emergency has been declared in California as wildfires, whipped up by fierce winds, continue to sweep through the area.
Tens of thousands of homes are under threat from the wildfires and some 180,000 people in the north have been ordered to leave their homes and roads around Santa Rosa were packed with cars as people tried to flee.
Another million people are expected to lose their supplies in the hours ahead.
The evacuation order encompasses a huge area of Sonoma County, including Santa Rosa.
The biggest blackouts in California’s history have already left a million people without electricity.
Power companies are trying to stop damaged cables from triggering new fires.
Sonoma has been ravaged by the Kincade Fire, which has burned through at least 30,000 acres of land.
Fears about the extent of the wildfires led PG&E to initiate a precautionary blackout expected to be the largest in state history.
PG&E said the power cuts would affect 940,000 households and businesses across 36 counties in northern California – hitting an estimated two million people.
In a statement, PG&E warned customers that they could be affected by a mass blackout, citing forecasts of potential extreme weather.
The warning came as the gas and electricity company faced scrutiny over its possible role in the fires.
The Kincade Fire in northern California began seven minutes after a nearby power line was damaged, but PG&E has not yet confirmed if the power glitch started the blaze.
PG&E is already seeking bankruptcy protection as it faces lawsuits over last year’s Camp Fire, which killed 85 people. The deadliest wildfire in the state’s history was sparked by ageing equipment owned by PG&E. It spawned billions of dollars in liability claims against the company.
In a video posted to Twitter on October 26, California Governor Gavin Newsom said the power cuts were “infuriating everyone, and rightfully so”.
“We are going to do our best to get through these high wind events… and get these lights back on and do everything in our power to make sure PG&E’s never in a position where they’re doing this to us again,” he said.
The Kincade Fire was about 10% contained as of October 27.
According to the state fire department, the fire was burning in remote, steep terrain, making access difficult.