Los Angeles, Sep 10 (IANS): California Governor Gavin Newsom announced the activation of the California National Guard to assist nearly 2,000 firefighters in battling a massive wildfire in California's San Bernardino County.

The fast-moving wildfire dubbed the Line Fire has scorched at least 23,600 acres (about 95.5 square km) with only 3 per cent containment as of Monday, forcing mandatory evacuation orders for over 11,000 people and putting more than 36,000 structures at risk, said Newsom in a news release on Monday.

"As the Line Fire continues to pose a threat to San Bernardino communities, we're pouring resources into this incident aggressively by deploying more air and ground support through the California National Guard," Xinhua news agency reported quoting Newsom.

"This is on top of nearly 2,000 firefighters, nearly 200 engines, and air assets we already have tackling this fire," he added. "California stands with these communities and has their backs."

The California National Guard will deploy four UH-60 Black Hawk helicopters for water bucket-dropping operations, and two C-130 aircraft with Modular Airborne Fire Fighting Systems -- a portable fire retardant delivery system, according to the news release.

The fire, which broke out on Thursday, has grown exponentially in size over the weekend due to soaring temperatures and critically dry vegetation amid a record-setting heat wave in California.

Newsom declared on Saturday a state of emergency in San Bernardino County to help ensure the availability of vital resources to suppress the fire.

"Fire activity on the Line Fire was moderated in the upper elevations in the overnight hours but remained active in the thermal belts.

The fire made short, intense runs in the slopes and the lighter fuels which allowed for growth," said the California Department of Forestry and Fire Protection.

At least five school and college districts in the region were closed for students and staff on Monday due to the impacts of the ongoing Line Fire, with more school districts being closed based on the assessment of conditions within their areas, said the San Bernardino County Superintendent of Schools.

The South Coast Air Quality Management District issued a wildfire smoke advisory for a large part of California.

"Based on satellite and webcam imagery, widespread smoke is over San Bernardino, Riverside, Orange, and Los Angeles Counties," said the agency.

PM 2.5 levels may reach the "Very Unhealthy" level or higher on Sunday night and Monday morning in southern Orange County, the Inland Empire, the San Bernardino Mountains, and surrounding areas, the agency warned.

Another wildfire called the Bridge Fire broke out on Sunday in the Angeles National Forest in Los Angeles County, nearly 100 km west of the Line Fire. The blaze has scorched over 1,250 acres (about 5 square km) with zero containment in the past 24 hours.

The Roblar Fire, which started on Saturday in San Diego County, has charred 950 acres (about 4 square km) with 25 per cent containment so far.