Nan, turn the volume down, OK?
Whoever made the comment about such horrors not happening in other countries and the glorification of Billy the Kid:
This is by no means our problem alone. Someone pointed out an incident in South Africa; he wasn't talking about one in ten years, either. Britain has also had its share, as do South American countries. I don't know this firsthand, but I know there's a forumite on TFL from Brazil. Perhaps he could confirm, but from what I hear that place is truly violent, especially Rio de Janeiro and Brasilia. Of course, these countries do have violent heroes (Robin Hood, anyone?) but Norway and Sweden love their Vikings and you don't hear about this stuff much there. Japan is the land of the Samurai, perhaps the most admired and certainly among the most brutal warriors of all time, but they don't have anything worse than us (not much better for high profile though--remember the cult with Sarin in the subway?) Of course, Japan is also a fairly repressive police state. One of the NRA mags once reported that they had a 98% confession rate, because they use methods that would flagrantly violate the constitution and even English common law.
As for music, I'm starting to think it may play a role. But it can't be the only scapegoat, and as one person pointed out, if you blame music you can't single out rap. These kids were supposedly Goth anyway; I doubt they would have been listening to much rap.
PARENTS PARENTS PARENTS PARENTS
Teachers, society.
The importance should be obvious. That is of course only my humble opinion.