Running Amok

Not exactly a new phenomena and not exactly confined to the West. Running amok is a term that has its origins in the Malayan Peninsula.

Quoting from Wikipedia:

"Running amok, sometimes referred to as simply amok (also spelled amuck or amuk), is derived from the Malay word mengamuk, meaning "to go mad with rage" (uncontrollable rage). In typical cases of running amok, someone, although having shown no previous sign of anger and/or any inclination to resort to violence, will acquire a weapon and in a sudden frenzy will attempt to kill or seriously injure everyone they meet."

Not a new phenomena to be sure. Not localised in the West either. According to Wikipedia, from the 1911 entry in Encyclopaedia Britannica:

"A Malay will suddenly and apparently without reason rush into the street armed with a kris or other weapons, and slash and cut at everybody he meets till he is killed. These frenzies were formerly regarded as due to sudden insanity. It is now, however, certain that the typical amok is the result of circumstances, such as domestic jealousy or gambling losses, which render a Malay desperate and weary of his life. It is, in fact, the Malay equivalent of suicide. The act of running amuck is probably due to causes over which the culprit has some amount of control, as the custom has now died out in the British possessions in the peninsula, the offenders probably objecting to being caught and tried in cold blood."

The crazed killer would, of course, be a parang or kris wielder then. Today, the nut would be wielding the current weapon in vogue and in production. In this case, Cho was wielding the Glock 19 and Walther P22.