U.S. School Shootings data, 1979-2011

Via Jessie Klein, The Bully Society: school shootings and the crisis of bullying in America’s schools, this graph deserves attention

The report details all the incidents, and provides some insight into motives and demographics.

Data on School Shootings

The NEA has a very useful crisis guide, which can be found here, detailing steps that can be taken before, during and after a crisis.