One of my classmates decided to threaten our teacher with an axe.

We knew that he had some problems and probably had some kind of mental sickness, but we had never thought about him going so far as taking an axe to the schoolgrounds, walking in tihe classroom and just coldly say "I hate you and I will kill you now". Fortunately our teacher grabbed him and threw him to the ground. The most crazy thing after that, is that the school decided to keep the boy in her class, and after some months she decided to leave. The boy changed to a special school for "Kids with extra needs" after the 6th grade.

And no all of this didn't happen in the US.

It happened in Denmark.