Efforts were underway Monday to clear vegetation around a brush fire that has burned 4,871 acres near the Cogswell Dam in the Angeles National Forest north of Azusa.
The fire was reported at 12:22 p.m. Sunday near the dam and West Fork Day Use area, according to a Los Angeles County Fire Department dispatcher.
As of Monday morning, the blaze — dubbed the “Bobcat Fire” — was still 0% contained, fire officials said.
Structures were threatened, according to Angeles National Forest officials, who said five engines, three hand crews, four helicopters, five fixed-wing aircraft and two water tenders were assigned to the fire.
Caltrans reported State Route 39 was closed in both directions from El Encanto Park near Cogswell Dam and the West Fork Picnic Area and Bridge.
A temporary flight restriction was in place over the fire area, and smoke was fouling the air in parts of L.A. County Sunday evening.
Temperatures in the forest were well above 100 degrees on Sunday, with only minor relief from the heat expected Monday.
Regulators issued a smoke advisory Monday, warning of unhealthy air quality in the San Gabriel Mountains, the east San Gabriel Valley and the Pomona-Walnut Valley.
“It is difficult to tell where smoke, ash or soot from a fire will go, or how winds will affect the level of these particles in the air, so we ask everyone to remember that smoke and ash can be harmful to health, even for people who are healthy,” said Dr. Muntu Davis, health officer for Los Angeles County. “If you can see smoke, soot, or ash, or you can smell smoke, pay attention to your immediate environment and take precautions to safeguard your health. These precautions are particularly important for children, older adults, and people with heart or lung diseases.”