This is an archived article and the information in the article may be outdated. Please look at the time stamp on the story to see when it was last updated.

Firefighters were able to prevent the Bobcat Fire from spreading beyond its footprint while raising its containment from 0% to 6% Thursday, officials said.

Winds continued to push the 23,890-acre wildfire northeast, further into the Angeles National Forest away from foothill communities. But that didn’t stop the smoke from shrouding much of Los Angeles County in a dingy haze.

Crews were working to protect homes in communities near the fire’s southern perimeter, including Azusa, Monrovia and Duarte, using Blackhawk helicopters to monitor the area, officials said on the federal InciWeb website.

The conditions were an improvement from Wednesday, when the blaze doubled in size with 0% containment. On Thursday, containment was achieved largely on the fire’s eastern flank, where it ran into the burn scar from last month’s Ranch2 Fire.

Firefighters expect to face greater challenges battling the northern portion of the fire, which is moving into ridges near Angeles Crest Highway, officials said.

Fire retardant drops are being conducted in that area, which includes steep, dry terrain that hasn’t burned in the last 60 years.

Powerful Santa Ana winds dragged the flames east Wednesday, making for heavy fire activity overnight near Crystal Lake. The fire jumped across Highway 39, where fire officials later reported making good progress.

But the blaze was extremely active Wednesday, spotting across long ranges, torching trees and visibly running across slopes — at one point threatening homes in the foothill communities as it tore through extremely dry brush, chaparral and tall grass in the steep, rugged terrain.

The smoke was so thick Wednesday, firefighting efforts from the air had to stop. But a sky crane helicopter and two additional hotshot crews joined the fight later in the day.

Air quality is forecast to remain poor Friday, and likely beyond. People across Los Angeles County are advised to limit outdoor activity and even indoor exertion.

Crews of more than 530 firefighters have responded to battle the flames, and officials expect to get additional fire and overhead resources after declaring the blaze a “Type 1 incident.”

“Containment dates are dependent on resource availability,” officials said. “Currently there are limited resources for fires statewide.”

Evacuation warnings are in effect for Monrovia, Bradbury, Sierra Madre, Altadena, Duarte and Pasadena.

Warnings were lifted for people in Arcadia, but city officials told residents to stay prepared.

“Residents should have evacuation plans in place, their emergency evacuation supplies organized, and their essential personal belongings easily accessible should fire conditions change. Vehicles should be fully fueled, facing out in the driveways, and ready to leave,” Arcadia city officials said.

A Red Cross evacuation center at Santa Anita Park has been closed, but it would reopen if needed, officials said. The organization says it has assisted 10 people affected by the blaze.

The fire ignited Sunday around noon near the Cogswell Dam and West Fork Day Use area, spreading rapidly amid record-breaking, triple-digit heat.

It’s still unclear what sparked the Bobcat Fire, and an investigation is ongoing.

State Route 39 remains closed in both directions at Old San Gabriel Canyon Road. State Route 2 is closed in both directions from east of Upper Big Tujunga Canyon Road to Big Pines.