Fire at Camp Pendleton Military Base in California as Crews Battle to Contain Blaze That Has Burned Over 145 Acres

A brush fire at a training area of Camp Pendleton, a U.S. Marine Corps military base in California's San Diego County, has spread to at least 145 acres.

The "forward spread [of the fire] has stopped" and 40 percent of the fire has been contained as of Tuesday morning, according to a post on the official Twitter account of Camp Pendleton.

The fire broke out Monday evening in the Mike Training Area at Marine Corps Base Camp Pendleton, a spokesperson for the base, 2nd Lt. Charlotte M. Dennis, confirmed to San Diego's NBC 7.

It is unknown whether any evacuations had taken place. The cause of the fire is under investigation.

The Camp Pendleton Fire Department is battling the fire.

The fire had blazed across eight acres by around 8 p.m. local time and 35 acres by 9:30 p.m. Firefighters reported the fire had been 20 percent contained when it spread to 50 acres by about 10:30 p.m. local time, NBC 7 reports.

There was a "slow rate of spread" by the time the fire spread to 35 acres, Camp Pendleton confirmed on Twitter.

The San Diego County Sheriff's Department warned on its official Twitter account: "If you live in @SDSO Fallbrook and @SDSOVista, be aware that smoke burning from a brush fire on Camp Pendleton may be visible in your area."

Newsweek has contacted Camp Pendleton for more information.

Orange and grey clouds of smoke were visible from distant hillsides, according to images shared by Twitter user @kevinmcclain06.

"Updated photo from 9:50pm PST. A little precipitation is starting to move in so there is a noticeable decrease in fire activity at this time," @kevinmcclain06 noted in a later post.

#CampPendelton fire visible here in Fallbrook. Such a hot day for the firefighters, hope they are safe," wrote Twitter user @CcahillCali.

Spanning more than 125,000 acres on the coast of Southern California, Camp Pendleton is the Marine Corps' largest West Coast expeditionary training facility.

Located around 38 miles from downtown San Diego and about 82 miles south of Los Angeles, its neighboring cities include Carlsbad, Escondido, Fallbrook, Oceanside, San Clemente, San Marcos, Temecula and Vista.

Camp Pendleton contains the largest undeveloped portion of coastline in Southern California and Southern California's only free-flowing river. Its ecosystem is home to beaches, bluffs, mesas, canyons and mountains and over 1,000 species of plants, fish and animals, some of which are reported to be either threatened or endangered, according to the Camp Pendleton website.