"The general public and the medical profession are familiar with the term running amok, the common usage of which refers to an irrational-acting individual who causes havoc. The term also describes
the homicidal and subsequent suicidal behavior of mentally unstable individuals that results in multiple fatalities and injuries to others...
Amok, or
running amok, is derived from the Malay word
mengamok, which means to make a furious and desperate charge. Captain Cook is credited with making the first outside observations and recordings of amok in the Malay tribesmen in 1770 during his around-the-world voyage. He described the affected individuals as behaving violently without apparent cause and indiscriminately killing or maiming villagers and animals in a frenzied attack.
Amok attacks involved an average of 10 victims and ended when the individual was subdued or “put down” by his fellow tribesmen, and frequently killed in the process....
Contemporary descriptions of multiple homicides by individuals are comparable to the case reports of amok. In the majority of contemporary cases, the slayings are sudden and unprovoked and committed by individuals with a history of mental illness. News media, witnesses, and police reports describe the attackers as being odd or angry persons, suggesting personality pathology or a paranoid disorder; or brooding and suffering from an acute loss, indicating a possible depressive disorder.
The number of victims in modern episodes is similar to the number in amok despite the fact that handguns and rifles are used in contrast to the Malay swords of 2 centuries ago...
Jin-Inn Teoh, a professor of psychiatry at the University of Aberdeen in London, reported in 1972 that amok behavior existed in all countries,
differing only in the methods and weapons used in the attacks."
Source