As you were walking towards the library you had to pass one of the deserted classrooms, no one ever went in there after the incident

Just as you walk by you hear some rumble and a vase falling to the floor and shattering, you stop and look at the door... before deciding to take a look... you pushed the door open, and the smell of dead filled your nostrils, you were about to leave when you heard a thud. You walked to the sound, and behind the teacher's counter was a person... you froze, the guy turned his head and looked at you... his mouth covered with blood, your eyes saw a girl with a bite mark, her skin pale... and eyes...