Its not commonplace. Far less commonplace per capita than vehicular related death by an order of magnitude.

Guys in UK did have gun apparently. Regular police showed up first and did nothing, until "armed police" were able to show up and shoot them. If you think guns or bombs are *hard to get in the UK you would be severely mistaken. They are less common, but even the criminals have less need for them. Most police arent even armed, let alone opposing citizenry.

UK is also has a far far higher rate of violent crime in general than the US.

For who could be free when every other man's humour might domineer over him? - John Locke (2nd Treatise, sect 57)