EE WAS INSTALLING ROOF BOLTS IN RIB TO SECURE WIRE MESH. BOLT WOULD NOT TIGHTEN AND EE BEGAN TO BRING THE BOLT OUT OF THE HOLE. THE BOLT HEAD WAS STUCK IN THE DRILL WRINCH. AS EE REACHED FOR THE WRENCH, EE INADVERTENTLY ACTIVATED THE DRILL ROTATION AND THE BEARING PLATE STRUCK EE IN THE FOREHEAD