All those killed were found in the same area of the town of Paradise, in the north of the state. At least four of them are believed to have perished in their cars, trying to escape in the panic and chaos of attempting to outrun the flames.
Another 35 people have been reported missing and three firefighters were injured.
Officials said the town's entire population of 26,000 was ordered to leave.
Early morning images from San Francisco show the city shrouded in smoke.
California fire captain Scott McLean said earlier that "pretty much the entire community of Paradise is destroyed", adding that the fire had grown to almost 110 square miles - four times its original size.
With two other huge fires also raging further south, 157,000 people have been forced from their homes.
Two separate fires are threatening the celebrity enclave of Malibu and the city of Thousand Oaks, still reeling from the recent mass shooting.
Those who live there have been warned of an "imminent threat" to their safety, with thousands of people being urged to flee however they can.
"It is critical that residents pay close attention to evacuation orders," the Los Angeles County Fire Department tweeted.
"This is a very dangerous wind-driven fire."
President Donald Trump has provided emergency funds for Butte, Ventura and Los Angeles counties - but he has also blamed forestry officials and threatened to stop funding forest management.
He tweeted: "There is no reason for these massive, deadly and costly forest fire in California except that forest management is so poor. Billions of dollars are given each year, with so many lives lost, all because of gross mismanagement of the forests. Remedy now, or no more Fed payments!"
US media reports that schools have been closed and animals have been moved out of the LA Zoo in Griffith Park.
No deaths have been reported in Malibu and Thousand Oaks
Rapper Kanye West and his wife Kim Kardashian West are among those in Malibu who have taken to social media to confirm that they are safe.
Actor Mark Hamill, who played Luke Skywalker in Star Wars, tweeted that the fire is "dangerously close to our home" but that he and his family are safe. He lauded the work of the fire service.
The first of the fires broke out on Thursday, northwest of Los Angeles, and roared south, with an estimated 75,000 homes evacuated in western Los Angeles County and eastern Ventura County.
Malibu has about 13,000 residents - including a number of celebrities - and many have shared pictures of busy roads as scores of cars take to the roads in a bid to escape.
Firefighting helicopters are using every source of water they can find - even filling up from residential swimming pools."
The LA County Sheriff's Office said it was receiving "many emergency phone calls" from people who "need our help to evacuate" and urged motorists in the area to be aware of emergency vehicles.
Strong blustery winds combined with dry conditions have helped the blaze spread, after weeks without rain and low humidity at the height of the wildfire season in north California.
Sky News' US correspondent Greg Milam, who is in Los Angeles, said: "What's driving this fire is the Santa Ana winds. Usually the winds here come off the water - they are wet and cool. But when they turn, they come from desert, down through the canyons, and they are dry and unpredictable.
"They come every year and they call them the 'devil winds'. They are a terrifying and deadly force of nature."
The 60mph winds have eased over the past few hours - but they are expected to strengthen again on Sunday and again Monday. No rain is forecast for the coming days.
In the San Francisco Bay area, some 180 miles away from Paradise, locals have been encouraged to stay indoors due to worsening air quality caused by smoke from the fire.
The air has become hazy and the smell of smoke is overwhelming, prompting officials to declare it unhealthy.
They are advising older people and children to stay indoors.