Tens of thousands of people have fled a fast-moving wildfire in northern California, some clutching babies and pets as they struck out on foot ahead of the flames that forced the evacuation of an entire town and destroyed hundreds of structures.

Everyone in Paradise, a community of 27,000 people about 180 miles north-east of San Francisco, was ordered to get out.

The extent of the injuries and damage was not immediately known.

Butte County CalFire Chief Darren Read said at a news conference that two firefighters and multiple residents were injured.

As she fled, Gina Oviedo described a devastating scene in which flames engulfed homes, sparked explosions and toppled utility poles.

“Things started exploding,” Ms Oviedo said. “People started getting out of their vehicles and running.”

At a late afternoon news conference, Mr Read said he had reports of several hundred destroyed structures in Paradise, but he cautioned that officials had not been able to assess yet.

He said officials will not have an exact count until they can get into the area.

“It’s a very dangerous and very serious situation,” Butte County Sheriff Kory Honea said.

“I’m driving through fire as we speak. We’re doing everything we can to get people out of the affected areas.”

The blaze erupted as windy weather swept the state, creating extreme fire danger.

A wind-whipped fire north of Los Angeles in Ventura County burned some 15,000 acres and at least one home in a matter of hours.

It prompted evacuations of a mobile home park, a state university campus and a small community. A nearby blaze was smaller at less than 1,000 acres but moving quickly.

California Wildfires
Flames consume a car and building in Paradise, California (Noah Berger/AP)

Acting California governor Gavin Newsom declared a state of emergency for the Northern California fire-stricken area.

Shari Bernacett said her husband tried to get people to leave the Paradise mobile home park they manage.

He “knocked on doors, yelled and screamed” to alert as many residents as possible, Ms Bernacett said.

“My husband tried his best to get everybody out. The whole hill’s on fire. God help us!” she said before breaking down crying.

She and her husband grabbed their dog, jumped in their pick-up truck and drove through flames before getting to safety, she said.

California Wildfire
A police officer directs traffic at a checkpoint in front of the advancing wildfire (Richard Vogel/AP)

Officials were sending as many firefighters as they could, Cal Fire spokesman Rick Carhart said.

“Every engine that we could put on the fire is on the fire right now, and more are coming,” he said.

“There are dozens of strike teams that we’re bringing in from all parts of the state.”

The sheriff confirmed reports that evacuees had to abandon their vehicles. He said rescuers were trying to put them in other vehicles.

“We’re working very hard to get people out. The message I want to get out is: If you can evacuate, you need to evacuate,” Mr Honea said.

The wildfire was reported around daybreak. Within six hours, it had grown to more than 26 square miles.

Thick gray smoke and ash filled the sky above Paradise and could be seen from miles away.

Fire officials said the flames were being fuelled by winds, low humidity, dry air and severely parched brush and ground from months without rain.

“Basically, we haven’t had rain since last May or before that,” said Mr Read, the fire chief. “Everything is a very receptive fuel bed. It’s a rapid rate of spread.”

At the hospital in Paradise, more than 60 patients were evacuated to other facilities, some buildings caught fire and were damaged, but the main facility, Adventist Health Feather River Hospital, was not, spokeswoman Jill Kinney said.

Some of the patients were initially turned around during their evacuation because of gridlocked traffic and later airlifted to other hospitals, along with some staff, Ms Kinney said.

Four hospital employees were briefly trapped in the basement and rescued by California Highway Patrol officers, Ms Kinney said.

The National Weather Service issued red-flag warnings for fire dangers in many areas of the state, saying low humidity and strong winds were expected to continue through Friday evening.