zlacker

Britain [not counting Northern Ireland] (about 1/6 the population of the US) and with really quite tight gun controls has had three murder sprees since 1987 that killed more than 10 people (all of which used guns). The worst of these (in 1987) led to a significant tightening of gun controls. Additional gun controls were also brought in after the 1996 attack on primary school in Scotland.

http://www.murderuk.com/mass_murderers.html

Other attacks have occurred at schools without guns including this one with a machete that resulted in injuries but no deaths: http://news.bbc.co.uk/onthisday/hi/dates/stories/july/8/news....

I would suggest that perhaps there is also a societal issue in the US compared to Britain causing these things (in addition to the affect of the larger population) but the most important aspect may be the greater availability of firearms that gives opportunity to people that may not carry out the act if they need time and preparation AND it greatly increases the lethality of attacks that do take place.

Note this excludes terrorism where numerous incidents have had a bigger death toll but those planned coordinated attacks and I think a different category from the sort of incident today.