Vermillion tried to retrieve his rifle wedged in the scabbard under his fallen horse , exposing himself to the Cowboys ' gunfire .
Firing his pistol , Earp shot Johnny Barnes in the chest and Milt Hicks in the arm .
Vermillion tried to retrieve Earp 's rifle wedged in the scabbard under his fallen horse , exposing himself to the Cowboys ' gunfire .
Firing his pistol , Earp shot Johnny Barnes in the chest and Milt Hicks in the arm .