Fire crews are responding this morning to a barn on fire on the 9000 block of Fraguero Road in Sonora.

The fire was reported about 10 a.m. and involves the barn and about a half-acre of wildland, said Cal Fire spokeswoman Lisa Williams. The fire was spreading at a moderate rate of speed, and at least one other structure is threatened.

Ground and air crews from Cal Fire and Tuolumne County Fire are on scene.