© Jill Torrance / Arizona Daily Star
Shelly Billingsley, center, receives some comforting words from Shelly Myrick, both of Springerville, in the evacuation center at Blue Ridge High School in Pinetop. At left, Lucille Ashcroft partakes of a meal prepared by volunteers.
Authorities say a raging wildfire that could become the largest in Arizona history is now 5 percent contained after charring more than 386,000 acres and destroying 22 homes in Greer.

The Wallow Fire has burned more than 525 square miles in Eastern Arizona. But fire officials Thursday evening said they were optimistic some residents who have been forced to flee the flames would be allowed back home by the weekend.

Full evacuations were still in place for Eagar, Springerville, Sunrise, Greer, Blue River, Alpine, Nutrioso and many subdivisions. More than 5,000 residences are threatened by the massive fire, officials said.

Fire officials reported earlier Thursday that six homes were burned overnight in Greer. But crews finished touring the area and assessing the damage by late afternoon and said 22 homes in Greer were destroyed and five other homes were damaged.

Officials also say 24 outbuildings in Greer were destroyed along with one vehicle.

A total of 29 residences have been destroyed so far.

Authorities said full containment is nowhere in sight, and power lines that supply much of West Texas and Southern New Mexico with electricity are also in jeopardy.

On Thursday, more than 3,000 firefighters got a break from nature when high winds driving the flames lost strength.

The fire, chewing through pine, fir and spruce in the White Mountains of Eastern Arizona, continued to burn on the edge of small towns scattered across the sparsely populated area.

A thick haze hung over the region and the blaze spread mostly uncontrolled, but fire officials did report a small containment figure. That was an improvement from a day earlier, when containment was zero percent.

The fierce winds that earlier in the week knocked small trees sideways abated, aiding fire crews who planned to use a DC-10 air tanker from California to dump fire retardant on the blaze's troublesome northwestern corner.

The DC-10 under contract to the state of California arrived Thursday morning and made several practice passes over parts of the fire before it was expected to begin laying 100-yard-wide, mile-and-a-half-long lines of water or retardant.

CalFire spokesman Daniel Berlant said the "supertanker" based in Victorville costs about $57,000 per day to operate for a minimum of five days. The federal government requested the plane and will reimburse the state.

The fire was half a mile from the New Mexico border Thursday and about a mile from Springerville and Eagar.

Crews had burned out a line of defense, and officials said residents of the two towns would probably be able to return to their homes Saturday.

Flames romped across the east side of the resort community of Greer.

"Greer is not out of danger," said Jim Whittington, a spokes-man for the firefighting efforts. "There's a lot of fire out there."

The flames threatened power and fiber-optic lines needed for cellphone and Internet service. "If we only had one problem area, we'd be able to knock it out," Whittington said.

El Paso Electric officials said Thursday that the utility has alternate power sources in case the fire reaches two of its main transmission lines, but they haven't ruled out asking users to cut down their consumption or scheduling blackouts.

The two high-voltage lines provide El Paso Electric with about 40 percent of its power supply, spokeswoman Teresa Souza said. The lines are connected to the Palo Verde nuclear power plant. El Paso Electric serves about 372,000 customers in West Texas and Southern New Mexico.

Fire officials in Arizona said there appeared to be no immediate threat to the power lines, but authorities in El Paso were preparing for the possibility.

Only the Rodeo-Chediski Fire was larger than this blaze. That fire in 2002 burned more than 468,000 acres. The Wallow Fire is expected to surpass that size.

The Arizona Daily Star, the Los Angeles Times and The Associated Press contributed to this report.