THE INJURED, A SECURITY GUARD, WAS MAKING HIS ROUNDS AND CHECKING PROPERTY WHEN HE OBSERVED 3 4 WHEELERS (ATV) PARKED NEAR A DOZER. GOT OUT OF VEHICLE, CHECKED DOZER, FOUND NOTHING NEAR A DO ZER. GOT OUT OF VEHICLE WHEN HE WAS WALKING BACKTOWARDS VEHICLE WHEN HE WAS STRUCK IN BACK OF HEAD AND KNOCKED UNCONSCIOUS FOR 30-40 MIN.