Don't know if these were posted before but the pattern is all the same dating back more that a hundred years. The only difference is that weapons are more efficient. We have always lived in a violent society.

"The Bath School disaster is the name given to three bombings in Bath Township, Michigan, on May 18, 1927, which killed 38 elementary school children, two teachers, and four other adults; at least 58 people were injured. The perpetrator first killed his wife, and committed suicide with his last explosion. Most of the victims were children in the second to sixth grades (7–14 years of age[1]) attending the Bath Consolidated School. Their deaths constitute the deadliest mass murder in a school in United States history.[2]"

1974 Olean High School shooting
1976 California State University
1976 California State University, Fullerton massacre
1979 Cleveland Elementary School shooting

http://en.wikipedia.org/wiki/School_shootings_in_the_United_States