More than 250,000 people have been forced to flee their homes to avoid three major blazes in the state.
Firefighters were powerless in stopping a wildfire destroying the northern town of Paradise, where nine people died and 35 are missing.
Another fire swept into the affluent southern beach resort of Malibu on Friday and has now doubled in size.
Two more people were reported to have died in that fire, known as the Woolsey, which now covers an area of 70,000 acres (28,000 hectares).
Among the towns under evacuation orders is Thousand Oaks, where a gunman killed 12 people in a rampage on Wednesday.
"The magnitude of the destruction of the fire is unbelievable and heartbreaking," said Mark Ghilarducci, of the California governor's office.
President Trump has responded by blaming what he called gross mismanagement of the forests and warned of funding cuts.
Meteorologists have warned that dangerous conditions may continue well into next week, but firefighters are hoping to take advantage of a temporary lull in the wind fanning the flames.
Where is the Woolsey Fire?
The blaze started on Thursday near Thousand Oaks, about 40 miles (64km) north-west of central Los Angeles. Another blaze, the Hill Fire, started at about the same time, also near Thousand Oaks.
On Friday, the flames jumped Highway 101 and headed into coastal areas.
All residents have been ordered to evacuate.
Los Angeles County sheriff's Chief John Benedict said on Saturday that two people had been found dead but provided no details on the deaths.
Malibu and nearby Calabasas are home to many celebrities.
The actor Martin Sheen was briefly reported missing but later found on the beach.
On Twitter, reality TV star Kim Kardashian said the home she shared with rapper Kanye West had been hit by the flames.
"Trying to get my mind off this fire... We are all safe and that's all that matters."
The singer Cher, who is performing in Las Vegas, tweeted that she was worried about her Malibu home.
The singer Lady Gaga said she had evacuated her home in Malibu, posting a video on Instagram that showed dark smoke billowing overhead.
Oscar-winning director Guillermo del Toro tweeted that he had evacuated, leaving behind his "Bleak House" museum collection of fantasy and horror memorabilia.
The fire has also reportedly destroyed one of the sets for the TV series Westworld and is threatening Malibu's Pepperdine University, a private residential college with more than 7,000 students.
Firefighters have not managed
to build containment barriers around the fire but hope to make some progress throughout Saturday.
Where is the Camp Fire?
The 20,000-acre (8,100-hectare) fire north of Sacramento started in the Plumas National Forest on Thursday and quickly engulfed the town of Paradise.
Residents fled for their lives as more than 6,700 homes and businesses were destroyed, making the fire the most destructive in the state's history. The flames moved so fast that some had to abandon their cars and escape the town on foot.
Butte County Sheriff Kory Honea told a news conference on Friday that the remains of five victims were found in or near burnt-out cars. Three others were found outside homes and one inside a home.
He said another 35 people were missing and three firefighters had been injured.
"This event was the worst-case scenario," he said. "It was the event we have feared for a long time."
Rescuers used a bulldozer to push abandoned cars out of the way in order to reach a hospital and evacuate patients as the fire engulfed the building, Butte County Supervisor Doug Teeter said.
"There's nothing left standing," said Scott Maclean, the state's forestry and fire protection spokesman.
The fire has now been partially contained.
Driving through walls of flame
By the BBC's James Cook, Paradise in California
Paradise is hell. A smouldering, sepia world in ruins. The air is acrid. Burning chemicals leave a bitter taste in your mouth.
Walking among the ashes of people's lives is eerie and awful. There is a profound sadness here. We pass a child's charred swing, a swimming pool filled with filth, and worst of all, a pet dog which did not survive.
Such was the intensity of the blaze that much of the debris is hard to recognise. Wafers of ash are drifting down like enormous snowflakes, smothering sound.
But it is not quite silent here. A sooty squirrel scrambles up a blackened tree in a panic. There are booms and creaks from burning trees and telegraph poles.
And soon, going from ruin to ruin, there will be the sound of those with the hardest job of all, checking to see if anyone was left behind.
Fire officials have also issued evacuation notices for parts of Chico, a town of 93,000 people north of Sacramento.
The three blazes are among 16 currently active fires in California. Officials have put most of Northern California under a Red Flag Warning, which means "extreme fire behaviour" can occur within 24 hours.
The region has grappled with serious wildfires in recent years, including the worst in the state's history - the Mendocino fire in 2018.