At least six homes burned and two firefighters were injured after a fast-moving wildfire blazed through parts of southern California on Friday.

Two firefighters were taken to the hospital with heat-related injuries from the Norte fire, officials said.

“As reported yesterday, we can confirm that six homes have been destroyed or damaged, there have been two firefighter injuries, and the cause is still under investigation,” an Orange County Fire Authority (OCFA) official shared in a statement via social media Saturday morning.

TJ McGovern, the OCFA chief, also confirmed, in a press conference Friday, that there have been no reports of resident injuries or deaths thus far.

McGovern attributed the severity of the wildfires to natural forces, such as weather and wind.

“Due to weather and topography, this fire moved fast. This was a wind-driven event,” McGovern said.

With wind gusts ranging from 50-70mph (80-110km/h), as of Saturday morning, the fire had spread to 570 acres (230 hectares) and was 5% contained, after OCFA crews worked throughout the night by land and air to aggressively attack the fire and strengthen containment lines.

The Norte fire started in the coastal city of San Clemente, and wind drove it into San Juan Capistrano.

It was one of several fires in the region hit by dry, warm gusts known as Santa Anas, which blow from the interior and toward the coast.

By Friday night, about 6,000 homes were under mandatory evacuation, affecting 16,000 residents. An evacuation shelter had opened in each city.

According to the National Weather Service, the Santa Ana winds would linger through Saturday, and the potential for extreme fire behavior and rapid spread could still rise.

To help prevent utility equipment from sparking new blazes, in northern California, nearly 62,000 customers in 26 counties had their electricity proactively turned off on Wednesday night, according to Pacific Gas and Electric Company.

More than 118,000 customers in California were without electricity as of Friday, according to poweroutage.com.

Destructive conditions fueled by a potentially historic El Niño brewing in the Pacific will continue to mount through the end of this year and into next.

But on the heels of the recent storm surge that battered the California coast, the weather whiplash has left residents reeling.

The NWS’s red flag warning for parts of southern California is in effect through Saturday night.

Just north of San Clemente, a wildfire dubbed the Henderson fire had burned 3,132 acres across parts of San Diego and was at 35% containment, according to Cal Fire.

Fire crews responded to the Henderson fire just before 2pm Thursday leading to the closure of Interstate 5.

Friday evening, the freeway closure was fully lifted, and at press time there were no reported injuries. The cause of the fire remains unknown and under investigation.

The weather service also issued a red flag warning for parts of central and northern California through Friday morning, saying any fires would spread rapidly.

The Associated Press contributed reporting