A policeman has been stabbed and his apparent attacker shot by officers in a major security incident at the British Houses of Parliament Wednesday afternoon. 

Around three shots rang out outside the Palace of Westminster after a man ran through the gates into the front yard of the parliamentary compound apparently waving a knife. 

Two people were seen being treated on the ground in New Palace Yard amid shouts and screams. 

An air ambulance landed in Parliament Square and a regular ambulance came in through the front gates as medics rushed to help the injured people. 

Armed police cleared the area around the incident and Parliament Square was closed to traffic. 

A Downing Street source confirmed that Prime Minister Theresa May was ‘OK’. 

Mrs May was seen being ushered into a silver Jaguar car as what sounded like gunfire rang out at Parliament during the incident at around 2.45pm. 

As the sitting in the House of Commons was suspended, Commons Leader David Lidington told MPs: ‘What I am able to say to the House is there has been a serious incident within the estate. 

‘It seems that a police officer has been stabbed, that the alleged assailant was shot by armed police. 

‘An air ambulance is currently attending the scene to remove the casualties. 

‘There are also reports of further violent incidents in the vicinity of the Palace of Westminster but I hope colleagues on all sides will appreciate that it’d be wrong of me to go into further details until we have confirmation from the police and from the House security authorities about what is going on.’ 

Witnesses described seeing a middle-aged man carrying a knife and running.

Jayne Wilkinson said: ‘We were taking photos of Big Ben and we saw all the people running towards us, and then there was an Asian guy in about his 40s carrying a knife about seven or eight inches long. 

‘And then there were three shots fired, and then we crossed the road and looked over. The man was on the floor with blood. 

‘He had a lightweight jacket on, dark trousers and a shirt. 

‘He was running through those gates, towards Parliament, and the police were chasing him.’ 

Her partner David Turner added: ‘There was a stampede of people running out. 

‘You saw the people and you thought ‘what the hell is going on’.’ 

After the incident, Radoslaw Sikorski posted a video to Twitter purporting to show people lying injured in the road on Westminster Bridge. 

Mr Sikorski, a senior fellow at Harvard’s Centre for European Studies, wrote: ‘A car on Westminster Bridge has just mowed down at least 5 people.’ 

Press Association Political Editor Andrew Woodcock witnessed the scenes unfolding from his office window overlooking New Palace Yard. 

‘I heard shouts and screams from outside and looked out, and there was a group of maybe 40 or 50 people running round the corner from Bridge Street into Parliament Square,’ said Mr Woodcock.