An early morning fire in a detached garage destroyed more than 20 antique cars Wednesday in Spokane Valley. The fire was in the 6900 block of N. Thierman. Spokane County Fire District 9 says it started in a large detached garage storing antique cars. The fire destroyed most of the vehicles inside and caused heavy damage to the building. More than 40 firefighters responded to the scene. One firefighter was treated at the scene for a back injury. The cause of the fire is under investigation.