“Four men were arrested Tuesday in London on suspicion of planning an act of terrorism, one that the city’s police commissioner described as ‘quite a serious case.’
Armed police officers assisted in the arrests of the men — two of whom are 20 years old, while the others are 21 — according to London’s Metropolitan Police. It is rare for police in Britain to execute warrants accompanied by armed officers, unless the threat is deemed serious.”
Source: UK police arrest 4 men suspected of terror plot – CNN.com