Los Angeles, Sep 12 (IANS): California Governor Gavin Newsom declared a state of emergency as three massive wildfires continue to rage across four counties in Southern California.

Newsom travelled to Highland on Wednesday and proclaimed a state of emergency in Los Angeles and San Bernardino counties in response to the Bridge Fire and in Orange and Riverside counties in response to the Airport Fire announced.

The governor's office said it had secured federal assistance to support the response to the fast-moving Bridge, Airport and Line fires, reports Xinhua news agency.

The fires, which broke out last week, escalated over the weekend due to soaring temperatures and critically dry vegetation amid a record-setting heat wave across Southern California.

On Saturday, Newsom declared a state of emergency for the Line Fire in San Bernardino County.

On Monday, he activated the California National Guard to assist nearly 2,000 firefighters in battling the wildfire.

As of Wednesday evening, the Line Fire had scorched over 36,481 acres (147.6 square km) and was at 18 per cent contained, forcing mandatory evacuation orders for thousands of people, the California Department of Forestry and Fire Protection (Cal Fire) said.

The Bridge Fire increased over ten times in size in 24 hours, exploding from 4,000 acres (16.2 square km) on Tuesday to over 50,000 acres (202.3 square km) with zero containment. The fire broke out on Sunday in the Angeles National Forest in Los Angeles County, nearly 100 km west of the Line Fire.

In an update Wednesday afternoon, officials said about 40 homes and cabins were destroyed by the blaze. There have been no reports of significant injuries or deaths.

Fire officials said that there are currently more than 1,000 structures threatened by the fire.

The third major wildfire in Southern California, the Airport fire, started Monday afternoon in Trabuco Canyon in Orange County. The fire had burned more than 23,000 acres (93.1 square km) by Wednesday night with five per cent containment.

The state has mobilised a massive air and ground response to contain the wildfires and protect communities, including nearly 6,000 boots on the ground and hundreds of engines, dozers and water tankers, as well as 51 helicopters and nine fixed-wing aircraft, said Newsom's office.