SPRINGERVILLE, Ariz. - A massive wildfire in eastern Arizona that has claimed more than 30 homes and cabins and forced nearly 10,000 people to flee was poised to move into New Mexico on Friday, threatening more towns and possibly endangering two major power lines that bring electricity from Arizona to West Texas.

The fire has burned 639 square miles of forest, an increase of 114 square miles from a day earlier, officials said.

"It's getting very, very close to the New Mexico state line," Jim Whittington, spokesman for the teams battling the fire, told reporters near Springerville Friday night. "This is really rugged country. There is a lot of potential" for the fire to grow.

Earlier in the day, Whittington said the lighter winds Thursday and Friday helped the 3,000 firefighters on the lines make progress, but critical fire conditions remain. High winds were expected to return with a vengeance Saturday.

"We have until then to get as much work as we can done and get to the point where we can sit back and watch the winds come," Whittington said.

Fire crews plan to try to strengthen what lines they've been able to establish and continue burning out forested areas in front of the main fire to try to stop its advance. It was officially just 6 percent contained Friday, but the actual numbers likely are higher, Whittington said.

The advances came on the fire's north side, near the working-class towns of Springerville and Eagar on the edge of the forest. Nearly 10,000 people have been evacuated from the two towns and from several mountain communities in the forest.

"I can't even speculate on when we can let people back in, but I can tell you we're not going to let people back in until we can be sure they will be safe and don't have to leave again," Whittington said.

On Friday, fire officials gave reporters the first look at two of the mountain communities - Alpine and Nutrioso - in nearly two weeks, driving them through the deserted resort towns and surrounding areas.

Some stands of trees in the forest were untouched while others looked like blackened matchsticks sticking up through lingering smoke. Firefighters were working in the area, using drip torches to light fires and burn out undergrowth.

Deer and elk grazed in unscorched areas, while wild turkeys walked through tall grass along the road. Two miles south of Alpine, whole hillsides of ponderosa were decimated.

The two Arizona-Texas power lines were still in the fire's path, although Whittington said he was less concerned about them Friday. El Paso Electric has warned its 372,000 customers that they may see rolling blackouts if the lines are cut.

The fire is the second-largest in state history and could eclipse the 2002 Rodeo-Chediski fire in size, although only a fraction of the homes have burned.

The Chediski began as a signal fire and merged with the Rodeo, which was intentionally set by a firefighter who needed work. Together they burned 732 square miles and destroyed 491 buildings.

The current Wallow Fire in the Apache-Sitgreaves National Forest has destroyed 31 homes or cabins, including 22 in the picturesque mountain community of Greer, Whittington said. Two dozen outbuildings and a truck also were lost and five homes damaged in Greer when the fire moved in Wednesday night.

A DC-10 tanker made three retardant drops near the community Thursday, and officials hope that by Saturday the threat will be much less.

Five homes were confirmed destroyed in Alpine and Nutrioso, and fire officials were trying to confirm if two others may have been lost.

Much of the growth toward New Mexico has been from fires started by crews trying to burn out fuels ahead of the blaze so it can be stopped, Whittington said. That technique allows the fires to be controlled and less hot. But there is little doubt it will cross the border, he said.

"This fire is eventually going to get there, so we want something to check it when it does," he said.

The fire doesn't appear to have moved into New Mexico yet, Catron County Undersheriff Ian Fletcher said. He said fire crews were cutting down trees and burning fuels along U.S. 180 near the Arizona border.

"I'm not sure when we're going to get to the point of it actually getting here," he said at midday Friday. Residents of about 100 homes in a subdivision near the border were still being kept away, and about the 200 residents of Luna were prepared to evacuate.

Both Luna and the county seat of Reserve were being powered by a large generator because of worries that electricity to the area would be cut, Fletcher said.

Deputies have gone to scattered homes in a remote area known as the Blue Range on the state line south of Luna to warn people that they should leave.

"Some have, some haven't," Fletcher said. "You always have some who say they'll be OK and then they have to scramble and try to get out at the last minute."

Whittington said Friday afternoon the fire may be moving into that area.

Authorities suspect the 408,887-acre blaze burning since May 29 was sparked by a campfire. It is the second-largest wildfire in state history.

New Mexico Gov. Susana Martinez visited the Reserve area Friday to discuss fire preparations. A day ago, Arizona Gov. Jan Brewer flew over burned areas in her state and met with evacuated residents in Lakeside.

"They're very resilient people up there," she said Thursday.