Three major wildfires near Spokane, Washington, have burned more than 7,700 acres and forced thousands of residents to evacuate.

The Old Trails, Fairview, and Autumn Lane fires have destroyed more than 600 structures, with officials warning the damage could increase.

Washington Gov. Bob Ferguson declared a statewide emergency and burn ban as more than 900 firefighters worked to contain the blazes.

Officials described the fires as one of the worst natural disasters in the region’s history, though no deaths have been reported, USA Today has reported.

The cause of the fires remains under investigation as Washington continues to battle a severe wildfire season.