Smoke from several wildfires hangs over the mountains of central and eastern Washington as firefighting helicopters work to contain the blazes. Aerial footage shows thick plumes rising from forests while helicopters scoop water from a lake before returning to the fire lines.

National Guard crews continue water-dropping operations as firefighters strengthen containment lines after cooler weather helped slow the spread. Officials warn that hotter, drier and windier conditions expected later this week could make firefighting more difficult.

The fires around Spokane have destroyed hundreds of buildings, forced tens of thousands of people to evacuate and remain under investigation after authorities said all three were started by people.