Southern California’s Fairview Fire has exploded in size, burning nearly 20K acres and forcing evacuations

(CNN) - The deadly Fairview Fire burning in Southern California has upended the lives of many Riverside County residents who said they felt blindsided by the flames that have been spreading rapidly since Monday.

Norman Nielsen, 65, told CNN Thursday he and his wife were going to bed when the sheriff came knocking on his door for mandatory evacuations. The couple has lived in the Fairview mobile home park for the last 10 years and scrambled thinking of what to pack on their way to the shelter.

"I didn't think it would ever come to this," Nielsen said. "(It's) scary because you ... never know when you might be the next one."

The firefighters came knocking on Kristina Delmark's door in Hemet, too, she said.

"I just grabbed my whole suitcase of paperwork for like, the kids... because I got four kids with me here, and I got my mom here," she said, adding that her husband stayed behind to wet the house so it does not get consumed by the flames.

"I'm very blessed that we're all together. And no matter where we are, that's home," she said.

Nielson and Delmark are just two of the presumably thousands in the Riverside County community who were under new evacuation orders this week as the Fairview Fire nearly quadrupled its reach from a day earlier.

As of Thursday afternoon, the fire has burned 18,657 acres and is only 5% contained, said Cal Fire, formally known as the California Department of Forestry and Fire Protection. This comes as the region battles a scorching heat wave, authorities said.

The cause of the fire, believed to have started Monday afternoon, is under investigation, Cal Fire said.

The blaze, which killed two people in a vehicle earlier this week, forced a string of new evacuation orders and warnings in the area that Cal Fire announced early Thursday. Details about how many people were affected by orders weren't immediately available.

A Red Cross shelter in Hemet opened Monday for evacuees, said shelter supervisor Ken Rieger.

"We've been running 24/7 ... and we have right now we have about 55 clients," he said, adding that the county animal control has been taking in people's pets for free. "A lot of them don't know if they have a home or not."

Fire is 'burning in all directions,' officials say

The blaze was "burning in all directions, on all flanks" Wednesday morning, Cal Fire Battalion Chief Josh Janssen said then.

The rapidly growing fire comes as California and many states on the West Coast swelter in a brutal heat wave, which is setting record high temperatures, fueling destructive wildfires and threatening rolling power shutoffs in California. The heat wave could last even longer because of the effects of a strengthening hurricane along Mexico's Pacific coast.

Schools in the Hemet Unified School District were closed because of the fire; it wasn't clear when they would reopen.

"Fire will become active with primary movement to the east due to the west winds. Steep drainages will aid the spread with the up canyon/up slope winds and heavy fuels," Cal Fire said online Thursday about the fire.

Circuit activity occurred "close in time" to when the blaze started, Southern California Edison said in a filing Monday, but the company said it is "not conceding that its equipment caused the wildfire."

That notification is intended to make California Public Utilities Commission aware of the incident so the agency can conduct an investigation, according to another document filed in coordination with the report.

As a result of the Fairview Fire, Riverside County declared an emergency. The proclamation has to go before the board of supervisors within seven days to be officially ratified, according to the county's website. The next board meeting is Tuesday.

"The emergency proclamation could help make the county eligible for potential federal and state assistance and cost reimbursement. In addition, the proclamation allows the county to more easily procure needed services and items to respond to the emergency," the county's website said.

Two people were killed in the fast-moving fire that swelled rapidly over parched vegetation. The two people were family members, California Highway Patrol Sgt. Brandi Swan said Wednesday.

"It appears as though the two victims found in the vehicle were trying to flee the fire," Swan said, adding the victims have not been identified.

A third woman, a relative of the two who died, was found outside of the vehicle, she said.

"She sustained some major injuries and she's recovering at a hospital," Swan said. "Always when there's a loss, we feel it, always. It is sad to think the fire moved so fast that they weren't able to leave."