The Columbine story line that took hold was that the student killers belonged to a group of outcasts called the Trench Coat Mafia, and were subjected to bullying, especially by jocks. Their motives supposedly was revenge, and they purportedly went hunting for athletes, nonwhites and those professing a love of God, before turning their guns on themselves. But almost none of this proved to be true, the newspaper says.
But author Dave Cullen characterizes the Columbine tragedy more as a failed school bombing rather than a successful school shooting. The two assailants did not seek out specific groups or individuals. They wanted to blow up the entire place and kill hundreds indiscriminately, and began using their weapons only after a bomb they built failed to detonate.
The “loners versus bullies” vengeance narrative was accepted and often applied to subsequent shootings in an effort to explain irrational acts. The result in some cases is parents' living in fear that their children could become victims.
Video from The New York Times: