Millions of Californians face having their power cut as firefighters continue to battle a surge in wildfires in the state.
Pacific Gas & Electric (PG&E) said it may have to turn off power in 36 counties amid forecasts of a "historic wind event", which it said could damage facilities and cause new fires.
The warning came as wildfires forced some 50,000 people from their homes.
A state of emergency has been declared in Los Angeles and Sonoma counties.
California's fire department says the state is experiencing "critical fire weather".
What is PG&E telling Californians?
PG&E on Friday warned about 850,000 customers – whose households are estimated to contain about 2 million people – that they "may be impacted" by a power cut between Saturday evening and midday on Monday, citing forecasts of potential extreme weather.
"PG&E will need to turn off power for safety several hours before the potentially damaging winds arrive," the company said in a statement.
"The weather event could be the most powerful in California in decades."
The company said high winds "pose a higher risk of damage and sparks on the electric system and rapid wildfire spread", adding that vegetation was especially vulnerable to fire because it had been dried out by previous winds.
The warning from PG&E came as the company faced scrutiny over its possible role in the fires.
The company says the Kincade Fire that started in northern California on Wednesday began seven minutes after a nearby power line was damaged.
It has not yet confirmed whether the power glitch sparked the Kincade Fire.
The deadliest wildfire in the state's history – which killed 85 people in northern California in 2018 – was caused by PG&E power lines.
Commenting on the latest fire, Governor Gavin Newsom said on Friday that the company "simply did not do their job". He condemned "years and years of greed, years and years of mismanagement in the utilities".
'Seconds to get out'
BBC correspondent Peter Bowes lives in the Santa Clarita area north of Los Angeles, where the Tick Fire has been raging.
"My partner was in the house and had just seconds to get out, to pick up the dog, throw the dog in the car – gently – just get out. It happened that quickly and all our neighbours did exactly the same thing," he said.
He later tweeted photos of the devastation.
Where are the major fires?
The Kincade Fire, which started on Wednesday, has burned through 21,900 acres (8,800 hectares) of land in Sonoma County – one of California's best-known wine regions.
More than 1,300 firefighters are tackling the blaze, which remains uncontained.
There are a number of other major fires, including:
- The Tick Fire in Los Angeles County has burned at least 4,300 acres in the Santa Clarita region
- The Old Water Fire in San Bernardino County has burned 95 acres, shutting off a major highway
- The Cabrillo Fire in San Mateo County, south of the town of Pescadero, has burnt about 95 acres
- The Sawday Fire in San Diego County, which began on Friday, has burned 97 acres, some 40 miles northeast of San Diego
- The Saddle Ridge Fire in Los Angeles County has burned more than 8,700 acres over the last 14 days
- The Muir Fire in Marin County has burned 58 hectares
- The Mines Fire in Alameda County has burned some 35 hectares since Thursday night
- The Miller Fire in San Diego County has burned about 37 hectares since Friday afternoon