Hundreds of structures were destroyed and thousands of people in Spokane County, Wash., remained under evacuation orders on Sunday as firefighters continued their efforts to knock back and control several blazes in the area.

Nearly 1,000 firefighters were combating at least three wildfires in Spokane, which is home to nearly 600,000 residents. More than 5,390 acres of land have been scorched and officials said there was no containment of the fires on Sunday afternoon.

Firefighters were racing to take advantage of weather conditions that had improved, but could worsen by Wednesday.

The National Weather Service said on Sunday morning that wind gusts would increase after noon and ease after midnight and that conditions would remain very dry, which could propel wildfires into residential areas. Officials said that the danger from fires was still elevated, but that winds were weaker than those on Saturday.

Large parts of Spokane County were under the highest level of evacuation order — Level 3 — and officials urged residents in the evacuation zone to leave immediately. About 4,000 structures were at risk of burning.

Videos on social media showed billowing smoke and orange-colored skies as cars in slow-moving traffic tried to get away from the fires. Others showed scorched communities, homes and vehicles.

Benjamin Cossel, the spokesman for the California Interagency Incident Management Team 7, which began leading the firefighting effort on Sunday morning after coming in from Oregon on Saturday, called the Spokane wildfires the “No. 1 priority fire in the nation,” because of its proximity to many homes.

More than a dozen other fires were also burning across Washington, but most of those were in less populated areas, affecting about 250,000 acres. About 4,000 firefighters were working across the state.

The Old Trails and Autumn Lane fires jumped the Spokane River on Saturday and were encroaching on a nearby canyon on Sunday, Mr. Cossel said, moving northwest away from the city of Spokane, but into the surrounding wilderness.
If the fire continues into the canyon, which local residents call Look Out Mountain, it could grow exponentially.

“The possibility for things to go sideways if it gets established in that canyon is pretty high,” he said, adding that “there is nothing really there to stop it.”

On Sunday, several aircraft dropped retardant and water on the flames.

Washington has been experiencing a record-breaking wildfire season, largely because of drought and heat. More than 1,000 fires have burned this year, covering about 425,000 acres, according to the Washington Department of Natural Resources.

On Saturday, forecasters with the National Weather Service had issued their most urgent alert — “a particularly dangerous situation” red-flag warning — for large parts of eastern Washington and northeastern Oregon. It marked the first time such a warning was issued in Washington, officials said.

Gov. Bob Ferguson also declared a state of emergency across Washington, pointing to drought conditions, unusually high temperatures and strong winds.

Response resources from across the nation have been called on to combat this blaze, Mr. Cossel said, depleting already limited reserves.

“We have multiple large incidents across the nation,” Mr. Cossel said, “resources are absolutely tapped.”