Dramatic Scenes: Man holds six-inch Knife to His Throat in Front of Buckingham Palace.

A man was tasered by police today after holding a knife to his throat outside Buckingham Palace.

The dramatic incident saw the man brandish two knives in front of hundreds of terrified tourists watching the popular Changing of the Guard event at 11.50am outside the palace in central London.

The scene was cordoned off 30 yards from the palace gates and an ambulance was nearby. Two knives with six-inch blades and a pair of Nike high top trainers lay inside the cordoned-off area.

Taser wire also lay on the floor with four plastic tubes for removing sharp objects. A hat and a black carrier bag containing paper material with a handkerchief beside it also lay on the ground.

Video and Pictures after the Cut:

Witness Grant Shepherd posted a video of the incident on YouTube after tweeting: 'Crazy man with a knife to his throat just stopped the Changing of the Guard at Buckingham Palace.'

In the YouTube video, the man takes a series of swipes at an officer as the stun gun is fired.

But as it connects he falls to the ground watched by hundreds of tourists who had assembled to watch the changing of the guard and take photographs of the palace.

Police at the scene were telling members of the public that a man ‘tried to make an exhibition of himself during the guard change’ and that there were ‘mental health issues’.

The Queen and Prince Philip were at the Sandringham Estate in Norfolk at the time of the incident. A Buckingham Palace spokesman said they would not comment as it was a police matter.

A spokesman for the Metropolitan Police said: ‘It was approximately 11.50. A man was seen outside the centre gate in possession of two knives.

‘He was not making threats to members of the public but he was challenged by police. He acted aggressively and a taser was discharged.

 ‘He is thought to be in his 50s. He was arrested on suspicion of affray and has been taken to a central London police station.’

A video on YouTube shows the man putting a blade to his own neck and shouting before police shoot him with the taser.