You are. 1966, University of Texas, 16 dead, 32 injured. 1999, Columbine High School, 15 dead, 21 injured. 2007, Virginia Tech, 33 dead, 23 injured. 2012, Aurora movie theater, 12 dead, 70 injured. 2012, Sandy Hook Elementary School, 28 dead, 2 injured.
What does every single one have in common? A crazy, but conscious of action, person decided to kill lots of people in a place where those victims couldn't possibly shoot back.