BOISE - Thunderstorms in west-central Idaho have sparked dozens of new wildfires, adding to several significant blazes across the state that have forced evacuations and threatened homes.

Crews are battling more wildfires in Idaho than in any other state, the National Interagency Fire Center reported Friday. About 312,600 acres - or roughly 490 square miles - of active fires were burning in Idaho, the agency said.

More than 60 lightning-caused blazes that erupted Thursday afternoon in southern Idaho and the Boise area are on lands managed by state and federal agencies, officials said.

An estimated 250 to 300 residents were evacuated in the Tamarack Resort area Thursday as firefighters battled the wind-fanned flames of the Hurd Fire, which more than doubled in size from 550 acres late Thursday to nearly 1,300 acres early Friday despite winds that were milder than predicted, U.S. Forest Service spokeswoman Laura Pramuk said.

At least 725 firefighters were working to contain the blaze, which has scorched more than 2 square miles but has not damaged property so far.

Pramuk said lighter winds on Friday were expected to allow crews to hold the blaze above housing subdivisions, but the agencies managing the wildfire remained leery of stronger gusts.

"There is the chance that the winds could pick up," Pramuk told The Associated Press.

The Valley County sheriff revised the evacuation order at noon Friday and some residents were allowed to return to their homes but warned they must be ready to leave again at a moment's notice.

The wildfire was 10 percent contained Friday afternoon.

The Long Butte Fire that has scorched 306,000 acres in the southern Idaho desert is 70 percent contained.

In central Idaho, firefighters are battling the Banner Fire that has burned more than 2,300 acres.

The lightning storm ignited some 60 fires in the Boise National Forest alone, said spokesman Dave Olson.

The blazes are scattered over a total of one million acres, or about 1,500 square miles, and many are in remote areas, which could make them difficult to reach, he said.

"It's just hard to get a handle on all those fires, they all started at once," Olson said.

At least one of those blazes was contained late Thursday when firefighters also responded to a wildfire at the Wilderness Ranch subdivision, where about 30 structures and homes were threatened.

The fire was contained and residents allowed back into their homes around 8 p.m., said Dalia Griffith, a freelance writer who has lived in the subdivision for seven years.

The 100-acre fire blackened a hillside but didn't appear to damage any residences, Griffith said.

"Fortunately by a stroke of luck, the lightning struck a pretty big hillside rather than a home," Griffith said.