Two men, including a police officer, were shot at outside Westminster on Wednesday, leading to the lower house of parliament suspending its proceedings, the media reported.
The House of Commons Speaker said that the shutdown will continue till further notice, the Independent reported.
Commons Leader David Lidington told MPs that a "police officer has been stabbed" and the "alleged assailant was shot by armed police" following a "serious" incident within the parliamentary estate.
London police said they were called to a firearms incident at Westminster Bridge near the British Parliament on Wednesday.
#PHOTOS: Chaotic scenes at #Westminster after #UKParliament shooting https://t.co/sTj4Erm7t2 pic.twitter.com/GSVzrXvcS3
— Al Arabiya English (@AlArabiya_Eng) March 22, 2017
"We were called at approx 2.40 p.m. to reports of an incident at Westminster Bridge. Being treated as a firearms incident - police on scene," the Metropolitan Police tweeted.
According to a witness, a policeman grabbed someone who was coming in the House and evicted him.
"I was told by one security guard to get out while another one told me to get in. As I walked in I heard a security guard get a radio message saying 'a policeman has been stabbed'".
Two men have been shot - one, presumably the assailant "who looked like he could be dead", said the report.
Staff inside Parliament were told to stay inside their offices.
Highlights:
Four-wheel drive car said to have driven over Westminster Bridge knocking down pedestrians this afternoon
Victims were said to have been left scattered in the road, with some knocked into the River Thames
Emergency services treated at least 10 injured people on the bridge, with one woman dead under a bus
'Asian' knifeman got into the grounds of Parliament where he reportedly stabbed a police officer
The 'middle-aged' attacker was then shot by armed officers as armed anti-terror police flooded the area
Parliament was suspended and the Prime Minister was rushed from the scene in her official car
Commons Leader David Lidington told MPs a 'police officer has been stabbed' and the 'alleged assailant was shot by armed police' following a 'serious' incident within the parliamentary estate.
Craig Mackay, the acting Met commissioner, is being treated as a 'significant witness' as he was at the scene when the attack started.
Terror on #WestminsterBridge after a car mows down pedestrians near #Parliament in #London 📷 @tobymelville @reuterspictures pic.twitter.com/rN9zTjspsH
— SundayTimesPictures (@STPictures) March 22, 2017
Witness 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'.'
Steve Voake, 55, was walking across the Westminster Bridge and saw at least two bodies lying on the road and one in the water.
Reports emerging of a #shooting outside #UKParliament in Westminster. Photo below c/o @Lukesteele4. pic.twitter.com/nHNeeHs94B
— James Tattersfield (@JTattersfield) March 22, 2017
'I saw a trainer lying in the road and when I looked more closely I saw that there were a couple of bodies the other side of the road,' he told the Press Association.
'And when I looked over the side there was another body lying in the water with blood all around it.'
Speaking to reporters outside the central London hospital, junior doctor Colleen Anderson from St Thomas' Hospital said a female pedestrian had died.
#BREAKING: #UK Police: Motives behind #UKParliament shooting in #Westminster still unclear https://t.co/tYn3b5yszg pic.twitter.com/SSYl9Mt0td
— Al Arabiya English (@AlArabiya_Eng) March 22, 2017
She also said she treated a police officer in his 30s with a head injury who had been taken to King's College Hospital.
She said: 'I confirmed one fatality. A woman. She was under the wheel of a bus. She died, confirmed her death at the scene.'