With high winds and low humidity expected to hinder their efforts, "there's not a thing happening that's on our side," said Larry Humphrey, who is leading the team fighting the fire.
"We're going to have wind now for 4 or 5 days it looks like, so the prognosis isn't real good for us," he told CBS News. "We're just being able to get out there and protect what we can."
Driven by winds reaching up to 60 mph, the fire roared across Mount Lemmon in less than an hour Thursday. Half the resort has been lost, 200 homes gone overnight, reports CBS News Correspondent Sandra Hughes.
Humphrey said firefighters managed to save about 60 homes and had thought they would be able to preserve another 30. But he said it could take two to three weeks to contain the fire, which had grown to around 4,000 acres.
The fire had forced the evacuation of Summerhaven, a community with hundreds of vacation homes and about 100 year-round residents, shortly after it started Tuesday.
"We're just hoping and praying that maybe our house was spared," said one resident.
"I don't know if the shop is even there and if there's a job to go back to," said another.
The town post office, a coffee house and the Alpine Lodge were destroyed while almost every other building on the town's main road was damaged by the fire, the Arizona Daily Star reported.
Firefighters had hoped to protect the homes on the mountain north of Tucson by making a stand along a trail about a mile away, but had to pull back when the intense blaze crossed the path.
"This is extremely rough country and it's also old growth timber so we have really heavy fuels, really steep country," said Humphrey. "A lot of this, we can't even safely put people in there."
The cause of the fire remains under investigation.
Humphrey said crews were hampered by exploding propane tanks and downed power lines.
One firefighter was taken to a local hospital for treatment, said Jim Payne, spokesman for the fire's incident management team. The exact injury was unknown.
The blaze consumed pine trees ravaged by years of drought and an infestation of tree-killing bark beetles. It is one of several wildfires in Arizona, where fire officials are braced for another busy year after seeing 630,000 acres burned in 2002.
Humphrey said the fire could still threaten radio transmitters and a radar facility on the mountain. Other pockets of homes could also eventually be threatened.
Summerhaven has an estimated 700 homes and cabins and a handful of businesses. Its population swells during weekends and summers as visitors drive up the Catalina Highway, the sole paved road winding its way up the 9,157-foot Mount Lemmon, to escape the desert heat.
Some residents cried, others hugged when they heard about the damage during a briefing for evacuees and owners of second homes in the community.
"At this point, I'm very calm at times," said Judy Epstein, a Summerhaven resident for six years. "I have waves in which I visualize the worst."
Gov. Janet Napolitano declared a state of emergency to free up money for firefighting efforts. She said she expects a similar declaration from the federal government.
"I have placed the National Guard on alert for immediate deployment, if the need arises," she said.