LGF quotes a report -

A well-connected source said there were more than 100,000 people in Britain from “completely militarised” regions, including Somalia and its neighbours in the Horn of Africa, and Afghanistan and territories bordering the country. “Every one of them knows how to use an AK-47,” said the source. “About 10 per cent can strip and reassemble such a weapon blindfolded, and probably a similar proportion have some knowledge of how to use military explosives. That adds up to tens of thousands of men.”

Banning guns, as was done in the UK, doesn't ban the heart of darkness from which the urge to menace and kill originates.   It merely turns a willful, blind eye towards it while demanding ever more from the other individuals who choose to engage and recognize the threat.  The sheep have positively invited the wolves.