The death toll has risen to nine people as thousands of properties have been destroyed in bushfires in northern and southern California in what has been described as the most destructive fires in 100 years.

Australians are among tens of thousands in California ordered to flee their homes as two monster bushfires roar through some of Los Angeles’ most exclusive suburbs.

In the north of the state, one wildfire incinerated most of a town of 30,000 people where flames moved so quickly firefighters and emergency services were left helpless.

Animals at the Los Angeles Zoo in Griffith Park have also been evacuated as a precaution.

Tens of thousands of residents in the beachside enclave of Malibu and the gated community of Hidden Hills, where celebrities including Kim Kardashian and Grammy Award winners Drake and The Weeknd live, were ordered to leave by authorities.

The Butte County Sheriff’s Office on Friday confirmed all nine people were found in Paradise including four found dead in their cars when the fire burned through 360 square kilometres and destroyed 6700 buildings – almost all of them homes.

When Paradise was evacuated, the order set off a desperate exodus in which many motorists got stuck in gridlocked traffic and abandoned their vehicles to flee on foot.

People reported seeing much of the community go up in flames, including homes, supermarkets, businesses, restaurants, schools and a retirement centre.
Rural areas fared little better.

Many homes have propane tanks that were exploding amid the flames.
The wind-driven flames also spread to the west and reached Chico, a city of 90,000 people.

Evacuees from Paradise sat in stunned silence on Friday outside a Chico church where they took refuge the night before.

They all had harrowing tales of a slow-motion escape from a fire so close they could feel the heat inside their vehicles as they sat stuck in a terrifying traffic jam.

When the order came to evacuate, it was like the entire town of 27,000 residents decided to leave at once, they said. Fire surrounded the evacuation route, and drivers panicked. Some crashed and others left their vehicles by the roadside.

Australian businessman Jon Sully, his wife Kath and their three children Spencer, Isabelle and Hamish, also had to make a mad dash from their Hidden Hills home as the fire line approached on Thursday night.

“We got the first mandatory at 7.06pm last night and packed the kids, dogs, passports, photos etc in the car,” Mr Sully, a co-founder of retail leasing platform StoreMatch, told AAP.

“We could see the red glow over the ridge that was flaring up so didn’t hesitate to go.”

They went to a friend’s house in nearby Agoura Hills but three hours later were forced to evacuate again when police on loudspeakers drove around the neighbourhood warning they were in peril.

They made it to a third friend’s house and spent a nervous night.

The threat remains for the region.

“The smoke was apocalyptic,” Mr Sully said.

Mandatory evacuations were also ordered in Thousand Oaks, the location of Wednesday night’s mass shooting when a former US Marine murdered 12 people at the Borderline Bar & Grill, including Ventura County Sheriff sergeant Ron Helus.

Many of the sheriffs and fire officers who were at the shooting had to turn to battling the wildfires.

The fire zone is a popular area for Australian expatriates to live.

More than 3000 hectares of land and at least 20 homes have been destroyed as two fires, powered by strong winds, were unstoppable as they headed west, jumped the 101 Freeway and roared towards Malibu on the coast.

Authorities said about 75,000 homes in Ventura and Los Angeles counties are under mandatory or voluntary evacuation orders and the number could grow.

In total, about 250,000 have been forced to evacuate.