The term "running amok" is a Malaysian loan word for the phenomenon of young men suddenly snapping and going on a murderous rampage. It's a universal phenomenon that probably has sociobiological, primate roots.
Other cultures have knife spree killers, or arsonists, or vehicular homiciders, or mad bombers. Guns however are a unique killing instrument in that they provide distance and removal. Killing someone with a knife is an almost intimate affair. You're likely to even get your victim's blood on you. So it's more terrifying. More to the point, a person with a knife can be overwhelmed by even a small group of people. A person with a gun cannot.
The point is that there's nothing in particular about American society that causes mass murder, it's that it's easier to do it. The means to do so are sold like candy bars at your local corner shop. Killing someone without a gun takes work. And it's inefficient.