EL DORADO COUNTY, Calif. (KTXL/AP) — Fire crews are battling the Caldor Fire in the El Dorado National Forest, as a Red Flag Warning remains in effect for Northern California until 8 p.m. Wednesday.

The fire exploded in size Tuesday. By Wednesday morning the Caldor Fire had burned 53,772 acres and was 0% contained.

More than 12,000 residents in multiple communities were ordered to evacuate Monday and Tuesday as the fast-moving flames moved through El Dorado County. Nearly 6,000 structures are threatened by the fire.

Cal Fire said Tuesday teams will move in to assess the damage when they’re able, but fire officials estimated that at least 50 homes had burned in the area since the fire erupted. 

Few homes were left standing in the Grizzly Flats area, where streets were littered with downed power lines and poles. Houses were reduced to smoldering ash and twisted metal with only chimneys rising above the ruins. A post office and elementary school were also destroyed.

Cal Fire also reported structure loss in Leoni Meadows.

A school official told NewsNation affiliate KTXL multiple schools are closed as a result of the Caldor Fire.

Cal Fire reported two civilians were injured overnight into Tuesday morning in Grizzly Flats. One person was seriously hurt and approached firefighters for help before being hospitalized. The other person was also severely injured and later flown to a local hospital.

The U.S. Forest Service said the fire began Saturday evening four miles south of Grizzly Flats and 2 miles east of Omo Ranch. Officials have announced an emergency closure of the El Dorado National Forest.

“It’s really tough to make access, there’s a lot of logging roads, they’re thin, they’re dirty, they’re unpaved and once you get in there it’s steep and rocky and otherwise inaccessible,” Metro Fire Battalion Chief Chris Vestal told KTXL Tuesday. 

The El Dorado County Sheriff’s Office said Sunday communities in the area “should be on alert and prepared to evacuate.” 

A map with current evacuation information can be found here.

“We know this fire has done things that nobody could have predicted, but that’s how firefighting has been in the state this year,” El Dorado National Forest Supervisor Chief Jeff Marsolais said at a briefing.

Joe Wilde, a Caldor Fire evacuee, described to KTXL Tuesday morning sifting through his family’s possessions before evacuating. 

“There’ll be a lot of stuff that’s gone,” Wilde said. “You have to be thankful because money can buy you things, but if anything happened to my boys, our pets or anything like that, they can’t be replaced.”

Belinda Wright lost her home in Grizzly Flats. 

“It’s sad. I’m a single mom of three kids and I lost everything,” Wright said. “I have my family. That’s all that matters.” 

Late Tuesday, Pacific Gas & Electric said it has begun shutting off power to as many as 51,000 customers in 18 Northern California counties to prevent wildfires for the first time since last year’s historically bad fire season.

The utility said the shutoffs were focused in the Sierra Nevada foothills, the North Coast, the North Valley and the North Bay mountains and could last into Wednesday afternoon.

The nation’s largest utility announced the blackouts as a precaution to prevent gusts from damaging power lines and sparking blazes.

The cause of the fire remains under investigation.