Updated

Containment of the 17-day-old wildfire burning in Southern California's Angeles National Forest increased Friday to 77 percent.

The size of the fire also was raised slightly to 160,557 acres, or just over 250 square miles.

The fire has been quiet, but burnout operations on the flanks of Mount Wilson, about 15 miles northeast of downtown Los Angeles, have again swathed the San Gabriel Mountains and foothill suburbs in smoky haze.

Firefighters had another hot and dry day with highs in the 90s and low 100s. Hotshot crews from 14 states are among the 3,500 firefighters working the blaze.

PHOTOS: California Wildfires Rage Near Los Angeles

On Thursday, Southern California heated up under the beginnings of a mini heatwave, but anticipated winds didn't appear.

Firefighters burned away vegetation below the northeast slope of Mount Wilson, which is crowned with TV and communications antennas for the region, and helicopters made runs in and out of the San Gabriel Mountains while expert hotshot crews worked deep in the wilderness, said U.S. Forest Service spokesman Nathan Judy.

The National Weather Service said high pressure was building in the region and winds were expected out of the north Thursday night and Friday with gusts to around 30 mph.

Air flow from the north sometimes produces dry Santa Ana winds which can whip up and spread fires.

New assessments of damage that occurred earlier in the fire increased the number of destroyed homes by four to 82.

The search for whoever started the fire is a homicide investigation because two firefighters were killed Aug. 30 when their truck plunged down a slope as fire approached a crew camp in the forest.

Elsewhere, a new blaze burned 125 acres in uninhabited Mias Canyon north of the Riverside County city of Banning, about 80 miles east of Los Angeles, but by midafternoon no flames were showing and containment was estimated at 35 percent, said Capt. Fernando Herrera of the state Department of Forestry and Fire Protection.

Helicopters and air tankers, including the giant water-dropping Martin Mars seaplane, were used.

Two firefighters suffered heat-related injuries.

Investigators trying to determine the cause of the fire were focusing on an area around an outbuilding that was destroyed, Herrera said.

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