The Associated Press

BOISE, Idaho — The legendary Sun Valley ski resort began running snow-making equipment Sunday to protect against a wildfire driven by winds so high that the surging flames couldn't be attacked by aircraft.

The famous resort town of Ketchum near Sun Valley, in central Idaho, took the unusual step of asking people to stay away. Officials told people to evacuate from more than 1,000 homes.

Air tankers were grounded for the second straight day by winds of up to 45 mph; the only hospital in the region ran with a reduced staff because it is in the evacuated area; and emergency responders had to deal with accidents caused by sightseers on key State Route 75.

The Sun Valley Resort began running its snow-making machines on Bald Mountain to protect the ski area from embers from the advancing blaze, which was within two miles.

"There's a lot of activity up here on this single highway in and out of this valley," said Gov. C.L. "Butch" Otter, who cut short a trip to Oklahoma on Sunday to fly to the area. "We really need people to stay away from up here and let these folks work."

The Castle Rock Fire, caused by lightning, ballooned to 54 square miles and was being fought by 1,400 firefighters and managers, including 11 helicopters, said Bob Beanblossom, fire information officer.

He said 100 engines were in the region protecting evacuated homes, some of which are worth millions. Access was being controlled by Idaho National Guard soldiers.

About 100 homes received mandatory evacuation orders last week, and 1,000 were ordered evacuated Saturday.

Tanya Keim, spokeswoman for St. Luke's Wood River Medical Center, said a handful of patients were discharged Sunday ahead of schedule.

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"Right now we are in lockdown," she said. "We are open for emergency services only. We may be asked to evacuate."