On Wednesday afternoon, an unidentified man drove a car into a group of people on Westminster bridge, injuring more than 40 before making his way to the Houses of Parliament, where he stabbed a police officer who later died of his injuries.
The assailant did not get far before a police officer – in one of the country's rare moments – shot and killed the attacker.
The average police officer in the UK (barring Northern Ireland) does not carry a firearm.
What is an AFO?
If however, a police officer can prove that they require a gun, they go through stringent training and become Authorised firearms officers (AFOs).
In 2016 there were 5,639 AFOs, making up 4.4 per cent of all police officers, and in that same year there were 14,753 police firearms operations, 85 per cent involved with Armed Response Vehicles (ARVs).
What this means, is that when a police officer does discharge a weapon, it demonstrates the particularly serious nature of the incident.
In this case, the terror attacks on London.
According to government data, in the year ending March 2016 there were 7 incidents in which firearms were discharged in England and Wales – the highest from the year 2009.
An extra 600 firearms officers have been promised to London following the Paris terrorist attacks.
A survey by the Metropolitan Police Federation found that almost half of Met police officers want more firearms specialists, and 75 per cent believe they should all be issued with Tasers.