Because there is a flood. luckily the flood put out the small fire. According to the quote there was a small little fire and then the kid makes a flood happen and has the school flood out. So there is no school to go to know and then they move away.
The school was flooded, why, because it was a prank.
Even though the kid thought it was a prank even though he just messed up the school and know no one can get to go to the school.
This is a funny story that says that you should prank anyone you want.