Mass murder should also be distinguished from spree murder, which involves several victims but not all in one place. In either case, the usual number of victims to meet the definition should be at least three. Mass murder has, in fact, been around longer historically and in more societies than serial murder. Community reaction is also different. As opposed to serial killers who instill lingering horror and lasting interest, society tends to get briefly shocked by mass murder and then returns to normal.
Victims just happen to be in the wrong place at the wrong time.
In many cases, the grudge is against the organization or bureaucracy. History of Violence 1. Transportation Hubs 2. Romantic Obsession 3. Convenience Stores 4.