Idaho ? A mandatory evacuation was ordered Saturday for residents of more than 1,000 homes south of Ketchum, where a massive wildfire raged and high winds grounded firefighting air tankers.

After three days of relative calm, the 39-square-mile fire was 38 percent contained, but embers blew ahead of the blaze and increased the threat of spot fires, fire spokesman Bob Beanblossom said.

“At this point in the mandatory evacuation, we’re giving people the opportunity to get out during the daylight and to keep the highways clear for emergency response vehicles,” said Kim Rogers, public information officer with the city of Ketchum.

Another 100 homes remained under a mandatory evacuation order from last weekend, including some worth millions of dollars in the resort area of central Idaho. A shelter was set up at a former high school in the town of Hailey, said Dick Rush, CEO of the American Red Cross for Idaho.

No structures had been reported lost to the lightning-sparked blaze, although winds were gusting to 25 mph, Beanblossom said.