Equip the shotgun and find a small area with a door. When at least two enemies come through, shoot the one that is closest to you. The other should run back through the door and go to a different part of the area you are in, as if you were somewhere else. Note: This will sometimes not work. Also, this can only be used for a short break in a fight; the enemy will somehow regain his or her senses and go back to you in after several seconds.