Updated Thursday, 5:10 p.m.

Tens of thousands of people were ordered to evacuate a fast-moving wildfire that exploded in size Thursday, threatening several Northern California communities and forcing panicked residents to race to help neighbors who had to drive through walls of flames to escape.

The Butte County Sheriff's Office said an evacuation order was issued for areas of Paradise, a town of about 27,000 people 180 miles northeast of San Francisco. Evacuation orders were also issued for Magalia, Concow, Butte Creek Canyon and Butte Valley.

Butte County Cal Fire Chief Darren Read said during a news conference that two firefighters and several civilians were injured, but the extent of injuries was unknown. He said the blaze has also destroyed a significant number of structures.

The blaze, known as the Camp Fire, had grown to more than 18,000 acres since Thursday morning and is 0 percent contained, according to Cal Fire.

The Butte County Sheriff's Office has been issuing evacuation orders on its Facebook page. See those orders below:

Acting Gov. Gavin Newsom has issued a state of emergency for Butte County.

The California Governor’s Office of Emergency Services (Cal OES) announced it has received a grant from the Federal Emergency Management Agency to ensure resources are available to fight the blaze. Cal OES, working with Cal Fire, has mobilized "strike teams and firefighters including aircraft, fire engines, dozers and water tenders."

Firefighters from Alameda and Marin counties, Oakland, Napa, Hayward, Berkeley, Piedmont and Fremont, among other Bay Area departments, are assembling in Butte County to battle the conflagration.

Rick Carhart, a Cal Fire spokesman, said the wildfire was reported at 6:30 a.m., affecting about 30,000 people in Paradise, Concow and other small communities.

"The blaze is being driven by fairly strong winds," Carhart said. "It's really dry and we have low humidity, and unfortunately those are great conditions for a fire to spread."

Current Road Closures

The Camp Fire has forced the closure of a number of roads, according to Caltrans. They include:

• State Route 70 in Butte and Plumas counties, from the Highway 149 junction in Butte County to the junction of SR-89/Greenville Wye in Plumas County
• Southbound Highway 99 from the Highway 32 junction to the junction at Highway 149
• State Route 191 at the junction of SR-70

The California Highway Patrol urges motorists to avoid the area.

North State Public Radio reporter Marc Albert spoke with KQED from an evacuation center off Highway 99 in South Chico, about 10 miles away from the fire. He said people are trying to flee the area.

"Traffic is bumper to bumper on the freeway inching southward," Albert said. "The Highway Patrol and county sheriffs have closed most of the roads in the area. People are absolutely either stunned or in some states of shock."

For more up-to-date traffic closures in the area, visit Caltrans' QuickMap.

Concerns Over Air Quality

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

The Bay Area Air Quality Management District issued an air quality advisory for smoke for the entire Bay Area and Sacramento area from midday Thursday through Friday.

The BAAQMD expects most of the smoke to remain aloft, but the public will likely see and smell smoke from the blaze.

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

Fleeing the Blaze

The Adventist Health Feather River Hospital in Paradise evacuated all its patients, given its close proximity to the fire, the facility said on its websites. It did not say how many patients were evacuated.

Enloe Medical Center in nearby Chico received 24 patients, spokeswoman Jolene Francis said.

Shary Bernacett said she and her husband tried to get people to leave the mobile home park they manage in Paradise and had minutes to evacuate as flames reached the east side of the town.

Bernacett said she and her husband "knocked on doors, yelled and screamed" to alert the residents of 53 mobile homes and recreational vehicles to leave.

"My husband tried his best to get everybody out. The whole hill's on fire. God help us!" Bernacett said, before breaking down crying.

She and her husband grabbed their dog, jumped in their pickup truck and drove through flames before getting to safety on Highway 99, she said.

Carhart said officials were sending as many crews as they could gather.

"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."

In Chico, west of the fire, resident Tina Greer said the care home where her disabled son lives with five other patients was evacuating. She said it takes time to pack the patient's medical equipment and medicine. Her 25-year-old son has cerebral palsy, needs a wheelchair to get around and is fed through a tube.

"They need time to prepare," she said. "There's a lot to move."

Greer said heavy ash was falling in Chico.

This report will be updated.

The Associated Press contributed to this report.