Police today said they are keeping an 'open mind' over whether a knifeman who pulled out a blade at the gates of Parliament was a terrorist.

The bearded man was tasered and surrounded by armed officers outside Carriage Gates - just yards from where PC Keith Palmer was stabbed to death in the Westminster terror attack.

A witness told the Mail Online the man appeared 'angry' and had his fists clenched before pulling the knife out when approached by officers.

The Met said counter-terrorism officers will investigate, although they have not declared it a terrorist incident.

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A man is arrested and led away by police after being arrested outside Parliament with a knife

A knifeman was tasered and held at gun point at the gates of Parliament today after a shout 'knife, knife, knife'

The man was patted down as he was held outside Parliament - very near where Pc Keith Palmer was killed during the Westminster terror attack earlier this year

Armed Police rushed to Palace of Westminster's Carriage Gates at around 11.10am and the Metropolitan Police confirmed it had arrested a man on suspicion of carrying a knife

A bang was heard and armed officers were seen standing over the man outisde Carriage Gates

The man was held by police outside Parliament before being taken away in a police van

Today's incident (pictured) is just yards from the scene of Khalid Masood's attack the palace in March. Pavement barriers are in place ahead of the Queen's Speech next week

Police officers inspect the pavement where the man was arrested. remnants of what is believed to be a police taser were seen on the floor

Armed police surrounded the man in seconds and he was taken away in a police van

Passers-by heard shouts of 'knife, knife, knife' and then saw officers pin the man down, at around 11.10am this morning.

The man, wearing black trousers and a grey sweatshirt, was held against the railings of Parliament by a number of armed police.

The Metropolitan Police confirmed today it had arrested a man on suspicion of carrying a knife. The suspect was driven away in a police van at 11.45am.

Today's incident is just yards from where Khalid Masood stabbed and killed PC Palmer in March.

It comes a year to the day since MP Jo Cox was murdered in her Batley and Spen constituency by white supremacist terror Thomas Mair.

The Met Police said: 'At this time it is too early to understand the motivation so we have not declared this a terrorist incident.

'However given the location, the circumstances and recent tragic events, the MPS Counter Terrorism Command will be investigating this incident.

'We remain open minded as to whether terrorism was a motive.'

Bradley Allen, 19, from Barking in east London, told MailOnline: 'I saw him, his fists were clenched and he seemed like an angry geezer.

'He shouted something and he went to run towards the gates and within seconds police had him pinned on the ground and were telling everyone to move back.

'It was over in seconds.'

He added: 'He had his fists clenched and looked angry, he was staring at me and my friend - I said to my mate he looked quite suspicious.

'And within seconds he had gone towards the front gate. It was so fast.

'Within seconds there were police all around and they had him pinned down. It was so fast. I didn't see any weapons.'

A Met spokesman confirmed an arrest had been made and there were no reports of any injuries.

Armed police surrounded the entrance to parliament as the man was arrested and taken away

Bradley Allen, 19, from Barking in east London, told MailOnline seeing the 'agitated' suspect with his fist clenched standing outside Parliament moments before he watched the incident unfold

The spokesman said: 'At 11:10hrs on Friday, 16 June, officers on routine duties near to the Carriage Gates entrance to the Palace of Westminster became aware of a man acting suspiciously.

'The officers approached the man in order to speak with him. The man reached for a knife, and police discharged a Taser.

'The man - aged in his 30s - was arrested for possession of a knife.

'Nobody was injured.

'The arrested man has been taken to a central London police station, where he remains in custody.'

Witnesses saw the police pat the man down and put items - including what looked to be the man's belt - into an evidence bag.

The incident took place just yards from where Khalid Masood launched an attack on Parliament on March 22 (pictured)

He was driven away from the scene in a police van just 30 minutes after the incident began.

The first sign of the incident was when a bang was heard inside the palace and armed officers scrambled to the scene.

Here is a video of the scene pic.twitter.com/a1MrTrv46L — kateferguson (@kateferguson4) June 16, 2017

Traffic was allowed to continue around Parliament Square and officers did not immediately clear the area.

Security has been heightened around the Palace of Westminster since the Masood attack incident, where he attempted to charge through the palace gates armed with knives.

His attack on Parliament came after he drove at pedestrians on Westminster Bridge.

The attack was the first of three to break through Britain's defences in the past three months.