When Zombies Attack

You take the bb gun and load it full with bbs. To practice your shooting a bit, you go to the window and open it, using the helpless zombies as target practice. You fire a bb into a particularly nasty zombie, hitting him in the butt. With a groan the zombie grabbed his bb wound and peered around, spotting you in the window. Instantly he took off running in an unzombie-like fashion towards the base of the apartment building, where he disappears through the front door. Moments later you hear knocking at your door.