SEATTLE - Thunderstorms and lightning threatened fire officials' plans to contain a large blaze in central Washington as hundreds of Washington and California residents returned home to find out whether their homes were spared.

In Idaho, authorities on Saturday issued a mandatory evacuation order for some 350 homes in the area around Featherville due to thick smoke. That town and the community of Pine, both recreation getaways in the mountains 105 miles northeast of Boise, remained in the path of a 130-square-mile wildfire that has been burning for two weeks.

Fire managers were concerned that poor visibility could hamper the evacuation process, fire spokesman David Eaker said. The smoke also prevented retardant bombers from reaching the fire and aerial reconnaissance flights from locating the fire's leading edge.

"It's a very active, very dangerous fire," fire information officer Steve Till said. Crews "were prepared for it, but civilians are probably much better not being here."

The Idaho Emergency Operations Center on Saturday assigned an Idaho National Guard helicopter to fires in the southwest part of the state to be available for medical evacuations if needed. Officials said the UH-72 Lakota helicopter and seven soldiers were scheduled to be stationed in Pine as early as Monday.

The Trinity Ridge Fire burning through timber grew 15 square miles overnight. High temperatures combined with low humidity and difficult terrain made it harder for the 1,082 firefighters assigned to the blaze.

Fire spokeswoman Lisa Machnik said Saturday that three firefighters suffered ankle and knee injuries because of the rough terrain.

To the west, many residents in Washington were returning to the south and east sides of a 35-square mile blaze near the town of Cle Elum in the Cascade Range, about 75 miles east of Seattle. That fire burned out of control for much of the week, destroying 70 residential properties and 210 other structures on the east side of the Cascades.

"People are finding a little bit of everything. Some homes were damaged, some homes were destroyed and some homes weren't even touched," Fred Slyfield, emergency management specialist for Kittitas County, said Saturday morning.

Nearly 1,000 firefighters and other personnel and eight helicopters were still building a line around the fire, which started Monday at a bridge construction project and exploded through dry grass, brush and trees. More than 400 people fled their homes. About 30 people are in local shelters, Slyfield said.

Fire danger remained high in the area, with hot, dry weather and a chance for storms and lightning expected Saturday evening.

"We're kind of on edge about that," said Mick Mueller, a spokesman at the fire command center.

Fire officials said crews are ready to respond quickly should lightning and winds trigger new fires in the area late Saturday, fire spokesman Matt Comisky said Saturday morning.

Firefighters in California made progress on some of the nearly dozen wildfires burning across that state. About 400 residents were allowed to return home in a rural area of San Diego County in the southern part of the state.

Crews also were gaining ground against a series of Northern California wildfires, but fire officials said lightning sparked more than a dozen new blazes in the area late Friday and early Saturday.

Most of the new fires were small, state fire spokesman Daniel Berlant said.

A light sprinkling of rain helped firefighters early Saturday helped crews battling a large fire in the Plumas National Forest, about 120 miles north of Sacramento. Crews had that blaze 34 percent contained.

The Chips fire has consumed more than 69 square miles and continued to threaten about 900 homes.

"We're encouraged by the progress our folks have been able to make," fire spokesman John Nichols said Saturday. "The weather last night and this morning helped the night crew get that much more done."

Associated Press writer Keith Ridler in Boise, Idaho, contributed to this report.