My teacher talked about this today.
Said sometimes people just explode.
The shooter targeted family and friends.

: http://www.cnn.com/2014/10/27/us/washington-school-shooting/index.html

http://www.nbcnews.com/storyline/marysville-school-shooting/what-we-know-about-shooting-marysville-pilchuck-high-school-washington-n234066