By Dan Whitcomb and Steve Gorman

LOS ANGELES (Reuters) - A fast-growing wildfire on Thursday destroyed at least 80 homes near the riverside community of Lake Isabella in central California, as a threat to populated areas from five other major blazes across the state diminished, authorities said.

The so-called Erskine Fire erupted around 4 p.m. in the foothills of Kern County about 42 miles (68 km) northeast of Bakersfield.

Within hours it exploded to cover between 3,000 and 5,000 acres (1,200 to 2,000 hectares)of drought-parched brush and grass, fire information website InciWeb said.

Fire officials also said power was knocked out as darkness fell and evacuation orders were in effect for more than 1,000 homes. Flames were threatening about 1,500 structures in the area by Thursday night, InciWeb added.

Footage of the blaze carried on the Kern County Fire Department's Facebook page showed flames consuming several homes and roaring through nearby foothills, as firefighting helicopters maneuvered around billowing black and white smoke.

The video showed entire blocks of homes devastated by the fire, with jets of flame seen shooting into the evening air from charred household gas canisters.

There were no immediate reports of injuries, though Kern County Fire Captain Tyler Townsend said some residents flouted evacuation orders. Up to 350 fire personnel were battling the blaze and hundreds more were en route, according to InciWeb.

Nearly 5,000 firefighters elsewhere around the state battled to control several major wildfires raging from the Klamath National Forest near Oregon to desert brush near the Mexico border.

Authorities said the danger was still high in some areas, despite making enough progress to lift evacuation orders for many residents who had been forced to flee earlier this week.

The combination of high temperatures, gusty winds and low humidity could challenge crews and raise the risk of new blazes, the mountains of Los Angeles, Ventura and Santa Barbara counties, the National Weather Service said.

In San Diego County, authorities lifted evacuation orders for the Mexican border community of Portrero on Thursday, saying crews had cut containment lines around a fifth of a wildfire that has blackened some 6,800 acres (2,752 hectares).

Evacuation orders remained in force for residents of two other mountain communities. Flames have already destroyed five homes and a dozen outbuildings since Sunday.

In foothills northeast of Los Angeles, authorities lifted evacuation orders on 534 homes on Wednesday as firefighters struggled to corral two wildfires that had merged, but evacuation orders stayed on 324 more homes.

The blaze had charred 5,200 acres of chaparral and grass by Thursday morning and containment lines had been drawn around 15 percent of the flames, authorities said.

The largest of the major California wildfires, the so-called Sherpa Fire in Santa Barbara County, was largely contained by Thursday, with most evacuation orders lifted.

The Pony Fire, ignited by a lightning strike on June 7 in the Klamath National Forest and which has blackened more than 2,800 acres, was 60 percent contained by Thursday.

(Additional reporting by Curtis Skinner in San Francisco; Editing by Alison Williams and Clarence Fernandez)