LOS ANGELES, July 21 (AFP) - Hundreds of residents fled their homes north of Los Angeles as a vicious new wildfire that has ravaged 4,000 hectares (10,000 acres) of land bore down on them, officials said Wednesday.
The blaze, fanned by gusts of wind and soaring summer temperatures in the US West, burned a historic bridge over a canyon and is threatening around 100 homes, according to officials battling the so-called "Crown" fire.
"It's very difficult because of the heat," said Anthony Penn of the Los Angeles County Fire Department. "The wind is averaging 10 miles (16 kilometers) per hour, and the vegetation is explosively dry."
US Forest Service spokeswoman Jody Noiron said officials were facing an unprecedented challenge as three separate blazes burn in the area three months ahead of the usual peak of annual fire season.
"What we're experiencing is pretty much unprecedented," she said of the firstorms that have collectively charred 12,800 hectares (32,000 acres) of vegetation and cost more than 25 million dollars to fight.
Around 2,400 firefighters backed by 186 fire engines, 21 water-dropping helicopters and 30 bulldozers -- used to clear firebreaks in the face of the advancing flames -- were battling the Crown fire.
The destruction of the bridge forced firefighters to drive long distances to reach the line of towering flames churning eastward and burning out of control.
The fire, which erupted Tuesday as firefighters battled a string of blazes across the region, has already run up around five million dollars' worth of damage and firefighting bills, Penn said.
Burning near Acton, the blaze has damaged a mobile home and an abandoned house and knocked out power lines as the flames leapt up hillsides left tinder dry by years of drought and intense heat.
The fire is burning about 20 kilometers (12 miles) northeast of another blaze that has been burning in the Angeles National Forest since Saturday, charring more than 2,400 hectares (6,000 acres).
But the "Foothill" fire was 81 percent contained Wednesday, and most of the 1,600 families evacuated from their homes in the area had returned home by Tuesday night and no buildings were destroyed, officials said.
Yet another blaze, the week-old "Pine" fire, which has ravaged 7,000 hectares (17,400 acres) of land, was still burning about 30 kilometers (20 miles) north of the Foothill fire but was 95 percent contained.