Much of California was on high alert Friday as fires tore through the state's south, destroying dozens of buildings, even as hundreds of thousands of people remained without power as a major utility company tried to avoid sparking deadly new blazes.
Officials issued a mandatory evacuation order for 100,000 people in the path of a fast-moving blaze in the San Fernando Valley in the northwest of Los Angeles.
The fire exploded overnight from 1,600 acres to 4,700 acres in a few hours, officials said.
Dubbed the Saddleridge fire, it was spread rapidly by seasonal high winds, known as the Santa Ana winds, and low humidity. No injuries had been attributed directly to the fire by early Friday, although one man died of a heart attack in the area affected, police said.
"We've calculated that the fire is moving at a rate of 800 acres per hour," said Ralph Terrazas, the chief of the Los Angeles Fire Department, adding that 1,000 firefighters were tackling the conflagration.
"We have approximately 23,000 residences that are impacted through a mandatory evacuation, and approximately 100,000 persons," said Michael Moore, the Los Angeles police chief.
"If you stay in a mandate closed area, we will not assure your safety," he said.
Another blaze swept through a mobile home park in hot, windy conditions 70 miles (115 kilometers) east of Los Angeles.
The Sandlewood fire, as it has been named, started when a truck driver dumped the rubbish in his vehicle on the side of the road after it caught fire, Riverside County Fire Department spokeswoman April Newman told the Los Angeles Times.
A helicopter and more than 200 firefighters were fighting the flames, the department said on its website, adding that 74 buildings had been destroyed.
There were no immediate reports of injuries, but authorities ordered some 1,900 homes in the area be evacuated.
The Los Angeles Police Department said on Twitter it had declared a "citywide tactical alert."
Evacuation centers are open for those forced to leave their homes, said LA mayor Eric Garcetti.
"The glow that surrounded us was so bright orange, it looked like it was in our backyard," one local resident told TV station KTLA 5.
Weather forecasters have warned of more strong winds and "extremely critical fire" conditions Friday and state authorities have issued their highest fire alert -- a red flag warning.
Some 540,000 people in the state were left in the dark Thursday after Pacific Gas & Electric switched off power in a bid to prevent a repeat of last year, when faulty lines sparked deadly infernos.
That number dropped to 312,000 by Thursday night, PG&E said, but many schools and universities had closed in northern parts of the state as people stocked up on gasoline, water, batteries and other basics, with frustration mounting at blackouts condemned by some as "third world."
"We're seeing a scale and scope of something that no state in the 21st century should experience," Governor Gavin Newsom said Thursday, blaming decades of what he called neglect and mismanagement by PG&E.
"What has occurred in the last 48 hours is kids staying home from school, parents that can't bathe their kids," he added. "Folks that come home from work, can't even find a way to get into their garage. You've got people that can't even access water, or medical supplies.
"This can't be, respectfully, the new normal," Newsom said, noting that the current weather conditions were certain to return.
Some 90 people died in last year's blazes across California.