The empty school.

The weather was really awful in the morning, but then in the afternoon the sun came out. The teachers gave the pupils an extra half an hour free time in the dinner hour. The three friends were sitting on top of a wall in the school yard, waiting for the bell to ring. Martin noticed that the bell never rang and he wondered, what’s going on? He went into the building and saw that no one was there. He called for his friends to go inside and look with him. They couldn’t  find anyone in the classrooms, so they took a look in the staff room. Neither did they find anyone there, so they went on to the principal's room. Still there was no one there. But they saw something strange, the window was open. They checked the staff dining room, but all they found there was half-eaten meals on the plates. They decided to search for the teachers everywhere, but noone was there...