Officers are trained to stop the threat

Those authorised to carry firearms - around 10 per cent of the 32,000 in the Metropolitan Police Service - are some of the best trained in the world responding to more than 10,000 calls each year.

But despite the dramatic growth in firearms operations, members of the Met's CO19 firearms squad open fire on average only twice a year.

It is in this context that the fatal shooting of Mark Saunders should be viewed.

The death of anyone at police hands is regrettable. The Independent Police Complaints Commission is investigating the incident and I cannot comment on the detail. However, it is important to consider the suggestion that police should "simply shoot to wound" when faced with an armed individual.

No police force in the world encourages its officers to shoot to wound in situations where there is believed to be a lethal threat to the public.

Officers in Britain are trained to "shoot to stop the threat" - in other words to incapacitate the person posing the threat - instantly. The best chance of achieving this is to fire at the torso, the largest part of the body.

In essence, officers have to be able to justify every bullet they fire. They are responsible in law for their decision to open fire.

Hitting an individual in the torso may kill and officers understand that they will have to show to independent investigators that potentially lethal force was necessary.

Furthermore, the first action of an officer, after incapacitating an individual, is to administer first aid.

Officers may also be called to account if they fail to shoot and the gunman then injures or kills.

Even the most accurate marksman might inflict a lethal injury if shooting to wound. But it is an unacceptably risky tactic. The gunman might be enraged and carry on shooting in an attempt to kill police or the public. For this reason, tasers and plastic bullets are unlikely to be used against a real firearm.

This is an exceptionally difficult area, requiring great skill, experience and judgment. It is not policing Hollywoodstyle, where guns can be shot out of hands.

We know that the public need a better understanding of the challenges. To further this, firearms officers are doing roadshows across London to explain how we train and recruit our officers, including the tactical and split-second decisions they have to make.