Bah, we in the US have been doing this for centuries ...
I know it's popular to talk about Columbine and more recent events in the US, but we have been ******* en masse for centuries, including young teens at school. It's only been more recently that such events have been sensationalized by the media.
"The worst" event is depending on how you calculate "worst," with Columbine and latter events being bested by one in the '60s, yet several others during the Depression (although those were common and often under-reported).
Before much of the modern media, the US had a history of even greater ********. Most of the bans on public display and other, local laws were not in conflict with the 2nd Amendment's right of ownership in the home and when outside the locale. E.g., the DC *** ban not only went beyond that, but did little to stem ***-related crime.