Wildfires fueled by soaring temperatures in the western United States have scorched thousands of acres, forcing hundreds of families to flee, US officials said Monday. The Line Fire in Southern California is only 3% contained and has spread across 20,000 acres. People are evacuating their homes and several structures are under threat.

17,000 people in Big Bear Valley are now under an evacuation warning as the Line Fire continues to grow. KTLA’s Sandra Mitchell reports live from Yucaipa with more.

Source: A blaze burning out of a control near Los Angeles sparked mandatory evacuations as it tore through swathes of tinder-dry California countryside around popular tourist spots.

The so-called Line Fire erupted on Thursday to the east of the city and exploded over the weekend, consuming more than 20,000 acres (8,000 hectares) and threatening tens of thousands of homes and other buildings.

Mandatory evacuation orders have been imposed and major roads shuttered, as more than 1,700 firefighters battle to contain the fast-moving flames.

Footage and photos from the scene show towering flames racing up the chaparral-covered hillsides.

Another blaze, north of Los Angeles, broke out on Sunday afternoon and had consumed 1,200 acres by Monday morning.

Firefighters ordered evacuations from the Bridge Fire as crews tackled it from the ground and from the air.

A punishing heat wave that has gripped the region since the middle of last week was exacerbating the problem, with high heat and gusty conditions making the spread of flames less predictable.

Aerials of line fire in San Bernardino County, California

• The Weather Channel: California Wildfire Threatens 35,000 Buildings
• AP: Thousands evacuate as wildfires rage outside Los Angeles and Reno, Nevada

AP: “We’re dealing with triple-digit temperatures and hard-to-reach steep areas where there has not been fire in decades, or in recorded history, so all that vegetation has led to significant fuel loads,” Carhart said.

Mara Rodriguez, a spokesperson with the San Bernardino County Sheriff’s Department, which issues evacuation orders, said nearly 5,000 homes fell under the existing orders and nearly 17,000 more were under evacuation warnings.