You can hide from the monsters in lockers. For example, when in the "Outbreak" stage on the second floor and in the locker room, go to the last locker (next to the window). If you have a zombie chasing you and he happens to break down the door, hide in the locker. The zombie will look around, walk around in circles, then pound on the door to leave. Once he leaves, you can exit from the locker. Note: This works for all stages.