Firefighters on Sunday battled a wildfire burning in steep, inaccessible terrain in central California, threatening at least 300 homes in or near a gated community, one day after a fast-moving brush fire in San Bernardino burned five homes and injured at least three people.

The brush fire broke out in San Bernardino and quickly spread to about 10 acres before firefighters got a handle on the blaze, a spokesman for the San Bernardino County Fire Department said.

Four hilltop homes were destroyed -- one had only a swimming pool remaining after being burned to its foundation, county fire Engineer Jeff Allen said. A fifth house sustained serious damage on the inside.

Authorities evacuated residents in the four blocks closest to the fire, Capt. Jeremy Kern said. Two firefighters and a civilian were treated for smoke inhalation or heat exhaustion.

The cause of the fire was under investigation.

The central California fire has grown to 2.8 square miles since it began Friday afternoon, Phil Neufeld, a spokesman for the Kern County Fire Department said Saturday. It is 20 percent contained.

Firefighters were focused on keeping the fire from climbing over a ridge and potentially threatening another 1,000 homes in Bear Valley Spring, a private community of 7,500 in the Tehachapi Mountains and several hundred homes in the Hart Flat community.

"It if blows over the ridge, it can cause damage," Neufeld said.

The fire was burning a number of dead trees devastated by California's four-year drought and a severe bark beetle infestation. Firefighters were hampered by the rough terrain, 20 mph winds and hot, dry weather.

The blaze is among 12 wildfires burning in California.

The fire is about 60 miles south of a deadly 75-square-mile blaze that broke out near Lake Isabella last week. That fire is 90 percent contained, and resources from it are being diverted to fight the new fire.

Meanwhile, fire crews are fighting two brush fires in Kittitas County in central Washington.

One blaze is burning about 5 miles east of Cle Elum, said Jim Duck, a spokesman with the Central Washington Interagency Communications Center. Residents of about several homes were told to leave the area immediately, he said.

No injuries have been reported, and no structures have burned, he said.

The fire was reported 1 p.m. Saturday and had burned an estimated 40 acres, the state Department of Natural Resources said.

Crews are also fighting on a smaller blaze that has burned 4 acres in South Cle Elum.

A voluntary evacuation order has been partially lifted as firefighters make significant progress in containing a southern Utah wildfire.

Fire officials say the blaze near Pine Valley, north of St. George, was 42 percent contained Saturday.

The voluntary evacuation now applies only to a small area that includes a portion of Lloyd Canyon. According to law enforcement, property owners there should be prepared to evacuate should conditions change.

The Washington County Sheriff's Office also opened the road into town to public traffic.

But campgrounds and hiking trails inside the Pine Valley Recreation Area and Dixie National Forest remain closed.

The fire, which has torched 2.5 square miles of rugged terrain so far, had previously forced evacuations.

More than 550 firefighters are working on structure protection and other strategies to halt the fire from spreading.

The fire started June 13 with a lightning strike on Saddle Mountain.

The Associated Press contributed to this report.