By JOHN ANTCZAK

LOS ANGELES — Surging wildfires on Tuesday forced new evacuations of hundreds of homes across the West, while firefighters worked to beat back a pair of huge adjacent blazes looming over suburban Los Angeles.

Near the U.S.-Mexico border southeast of San Diego a two-day-old, 12-square-mile wildfire took a large leap and forced the evacuation of about 600 homes and more than 1,500 people in the community of Lake Morena Village. Previously only about 75 people had evacuated.

In Utah, officials have evacuated about 100 homes from a mountain town in the southwest of the state as a wildfire less than a mile away is moving down a rocky slope toward the community of Pine Valley. The blaze is less than a square mile but moving dangerously close to homes in difficult terrain, officials said.

In Southern California, two adjacent fires in the San Gabriel Mountains 20 miles northeast of Los Angeles burned out of control but had not destroyed any homes while their combined size grew to more than 8 square miles.

About 770 homes in the foothill city of Duarte were under evacuation orders and residents of Bradbury and Monrovia just to the west were urged to be ready to leave immediately if given the word.

A 4 a.m. wind shift started bringing the fire down the mountains but a helicopter making nighttime water drops slowed the advance. Significant progress, however, was made overnight on the east side of Duarte, where flames creeped down to the bottom of slopes behind homes and firefighters extinguished them.

The two fires erupted separately Monday and scared homeowners before burning mostly away from the cities.

Charlie Downing, out of breath and with his shirt off because of the heat, said when he first smelled fire and felt heat that he ran outside of his house and was astonished by the size and nearness of the flames.

“I came running over just to look and it was 15 to 20 feet in the air,” Downing told reporters. “By the time I came back and told my grandma and my kids to get in the car, it was right by the car.”

He and two neighbors sprayed the flames with their yard hoses until firefighters arrived minutes later.

Two towering columns of smoke rose from the mountain range.

Elsewhere, crews made progress against a week-old blaze in rugged coastal mountains west of Santa Barbara, boosting containment to 70 percent.

About 270 homes and other buildings were threatened by the blaze.

Other blazes burned wide swaths across Arizona and New Mexico, where firefighters also faced blistering heat.