No violence is really ever shown. A teacher is shot just off-screen, and we see his wound and see him die. Several bodies of students are seen, some with wounds (about half of which are bloody). A SWAT officer picks up the body of a student that was slouching on a desk, and we see a large bloodstain on the desk the student was leaning over.

1 bulls*it, 1 s*it, 1 God*amn

the movie isnt really frightening although while the shooting is happening there is suspense but that is all