Firefighters stood guard around a $200 million mountaintop observatory and wrapped sheets of aluminum around summer cabins Tuesday to protect them from an approaching wildfire.

The flames were less than two miles from Turkey Flat, a community of 74 cabins on the side of Mount Graham (search). Officials said the fire could spread quickly in the hot, dry weather, but no structures had burned as of Tuesday evening.

"This was a big active day for fire but we're still holding our own," said Dan Oltrogge, an incident commander for the team fighting the fire.

The lightning-sparked fire and a nearby fire on another part of the mountain in southeastern Arizona had earlier prompted evacuation of the Mount Graham International Observatory (search) and a total of about 90 cabins in Turkey Flat and another community.

Oltrogge said the fires had charred between 25,000 and 30,000 acres combined. He didn't have a breakdown on the size of each fire. They were 10 percent contained.

The observatory's eight buildings and 8½ acres of pine forest on Mount Graham's 10,470-foot Emerald Peak (search) were surrounded by a 200-foot-wide clearing, and fire crews planned more controlled burns to expand the buffer zone. It also has a sprinkler system that officials said would be turned on if flames came within a few hundred yards. Fire officials said that could happen by Wednesday.

Officials said although the observatory building would probably not burn, smoke and heat could damage its delicate instruments.

The observatory, an extension of the University of Arizona, has two operating telescopes and the $120 million Large Binocular Telescope (search), which is under construction.

Fire crews' main concern Tuesday was Turkey Flat, lower on the mountain about 150 miles southeast of Phoenix. Firefighters removed heavy vegetation from around cabins and drenched the homes with water, while wrapping them with aluminum to deflect heat.

"I don't want anyone's life put in jeopardy because of my cabin," said Richard Lines, 59, who has owned his Turkey Flat summer home for 25 years. "Everything is replaceable, but a life is not."

Elsewhere in Arizona, a fire had blackened 85,000 acres of the Tonto National Forest near Payson, a town of some 14,000 people. The blaze was not threatening any homes or communities.

In central Washington state, firefighters attacking two wildfires that have burned nearly 10,000 acres near Lake Chelan braced Tuesday for expected high winds.

The winds could blow one of the fire, which flared to 3,200 acres Tuesday about 3 miles east of the lake, toward houses and other structures, said Ray Steiger, a spokesman with the incident management team.

Firefighters were building fire lines to protect two small residential subdivisions. Officials recommended evacuation to residents of about 45 homes.

In Alaska, an evacuation order remained in effect Tuesday for 277 homes threatened by a 307,000-acre fire north of Fairbanks.