Firefighters are battling Oregon's Flat Fire covering 22,000 acres and threatening hundreds of structures despite recent weather improvements and new containment lines.

Ten structures — including four homes — have been destroyed by a wildfire sweeping through central Oregon as thousands of homes in the state and in Northern California wine country remained under evacuation orders Monday.

Thousands of homes are under evacuation orders, including about 4,000 around Sisters, Oregon, because of the growing Flat fire.