100 Theme Challenge: Insanity

It started out like a normal day.  The bell had just rung, and Nia Toney was taking her seat in homeroom.   Everyone whispered to each other, giggled, and looked at her.  But never talked to her.  Yep, just a normal day.  But one I remember well.
Nia, you see, had been subject to this shun for the whole year.  No one is really sure why.  Kids sure can be cruel.  My only regret with her is that I never did anything about it.  Never spoke to her.  Hardly looked at her.  Which is why what happened that day is partially my fault.  Partially all our faults.  Everyone but Nia.
It was fourth period, I think.  English.  The teacher had told us to read our own books.  Nia was immersed in whatever her book-of-the-week was, I pulled out my copy of the latest in my favorite series.  Then, the whispering started.  I heard giggles.  Then, the unthinkable happened.  Nia pulled out a knife and slashed the girl in the face with it.
She started wailing, smashing everything in sight.  The teacher tried to stop her, but that was over quick.  Mrs. Myin lay on the floor in seconds.  That's when I blacked out.  When I woke up, I was in the nurse's office and seven people were dead.  
And it started as a normal day.