An out-of-control  wildfire prompted over 4,000 residents to evacuateafter spreading across northern California.

The Park Fire in Butte County was stiill growing quickly on Saturday morning, affecting some 307,369 acres (1,244 square kilometers) according to the California Department of Forestry and Fire Protection (Cal Fire).

Officials said it was still at "zero percent" containment.

What do we know about the fire?

The fire started on Wednesday near Chico, in Butte County, where some 400 residents have since been evacuated. It reached the neighboring Tehama County within hours, devastating a wide area of it.

It is believed to have been started by an arsonist, who pushed a burning car into a ravine. A 42-year-old suspect was arrested on Thursday. He will be held without bail until a court appearance next week.

Over 1,600 fire fighters have been dispatched to battle the Park Fire. The blaze has so far destroyed some 134 structures.

"The biggest challenge with this fire is getting to it," said Fire Captain Dan Collins. "It's steep land with almost no roads. It's hard to get our people and equipment to the fire lines."

The National Weather Service has issued a Red Flag Warning for the region through Friday night. It predicted "critical" fire weather conditions.

'You have to be prepared to go'

Authorities have continued to call on people in affected areas to evacuate immediately.

"You have to be prepared to go," Butte County Sheriff Kory Honea warned area residents. "This county has seen time and time again where people have waited too long and they have lost their lives."

Chico resident Carli Parker told the AP news agency she and her family had decided to flee when the fire began burning across the street.

"I think I felt like I was in danger because the police had come to our house because we had signed up for early evacuation warnings, and they were running to their vehicle after telling us that we need to self-evacuate and they wouldn't come back," the mother of five said.

The fire is burning merely 25 miles (roughly 40 kilometers) away from Paradise, where a 2018 fire devastated the city and killed 85 people.

California is experiencing some 20 active wildfires, in a seemingly early start to a wildfire season that could prove intense.

rmt/dj (AFP, AP, Reuters)