(Update: Pennsylvania has no monopoly on multi-victim attacks, and the PHB thoughts and prayers are with the individuals dealing with the Feb 26 2015 Missouri shootings. As of this time, details are sketchy, but it appears to be another instance of "running amok.")
With today's horrific Pennsylvania high school knife attack occurring just days after the second Fort Hood shooting, the Population Health Blog naturally sought refuge in the scientific literature.
What's going on?
Here's a highly informative - if somewhat old - article that makes the following observations:
1. "Running amok" (from the Malay word mengamok, meaning to "make a furious and desperate charge") attacks by a single disturbed individual leading to multiple casualties with or without suicide was first reported in the 1700s by European explorers of Southeast Asia. It was thought that the phenomenon was culturally unique to the indigenous peoples of the Philippines, Laos and Papua New Guinea, but heightened awareness in the 1800's eventually led to the conclusion that this is a rare but worldwide phenomenon.
2. Brooding prior to the episode is common. Attackers who survive often can't recall the event. This is far more common among males. Suicidal intent is more common among men who are 45 years of age or greater.
3. While culture and the availability of weapons determines how an attack is carried out, an underlying commonality is the presence of one or more underlying psychiatric disorders, including psychotic depression, bipolar disease, a personality disorder, schizophrenia and drug or alcohol abuse. Those conditions are typically provoked by a personal loss or stress. That leads to combined suicidal and homicidal ideation driven by anger, hopelessness and a quest for revenge.
4. Yet, while practically everyone who "runs amok" has severe mental illness, very few persons with mental illness "run amok." Health providers should worry about the possibility of it happening if there is a history of violent threats or behavior, a recent stress (job loss, conflicts, loss of a loved one), or paranoia, especially if there are "command" hallucinations.
5. Primary care physicians, employee assistance programs, health insurers and community health clinics are the first line of defense. Family and social support networks have an important role to play in giving these individuals other options. Yet, other than addressing the social isolation and the treatment of the underlying mental illness, there is no specific treatment for running amok.
The full text of this article is not available, but it says that while school shootings are up, the incidence of running amok has not increased. The three "prototypes" are 1) struggling adolescents, 2) persons with paranoid psychoses and 3) adults with personality disorders who have experienced a breakdown of a close relationship.