Grass Valley and Nevada City fire as well as Nevada County Consolidated, Ophir Hill and Cal Fire Engines responded to the 400 block of East Main Street Grass Valley at 8:20 Tuesday evening to the report of a structure fire. The first units to arrive observed smoke and fire coming from a window of the vacant structure. The Truck crew cut holes in the roof to vent the smoke from the structure while engine crews made an interior attack. Twenty five personnel spent almost two and a half hours extinguishing the fire. There were no injuries during the fire and the cause remains under investigation.