Britain Houses of Parliament are in lockdown after a knifeman reportedly charged through the gates of Westminster into the front yard of the parliamentary compound.
The alleged assailant was shot by police, according to the leader of the House of Commons, in London about 2.45pm Wednesday (1.45am Thursday AEDT).
A witness alleged assailant was seen walking towards a policeman with a knife in his hand, having already assaulted another policeman.
Witnesses also say a car mowed down a dozen pedestrians on Westminster Bridge before crashing into the gates outside Portcullis House, The Sun reports.
Two people were seen to be lying within Old Palace Yard, immediately outside Westminster Hall, News.com said on Wednesday.
Earlier reports suggested sounds of an explosion were heard, but this has not been confirmed.
A witness reported: “We heard a loud bang, lots of shouting and men running around.
Someone rushed through, attacked a policeman.
“He appeared to be carrying a knife or a gun. We then heard gunfire, five or six rounds.
“The man approaching one of the police officers with a knife.”
A medical helicopter has landed outside the Houses Parliament to treat victims and a Hazardous Area Response Team has been dispatched.
The sitting in the House of Commons has been suspended while police officers sealed off the area around the incident.
Staff inside Parliament were told to stay in their offices and stay away from the window.
Immediately before the incident, a crowd of passers-by was seen running from the direction of Westminster Bridge and around the corner into Parliament Square.
Met Police have said: “We were called at approx 2:40pm to reports of an incident at #Westminster Bridge. Being treated as a firearms incident — police on scene.”
US President Donald Trump has reportedly been briefed on the incident.
BBC Breaking NewsVerified account @BBCBreaking tweet on the issue “police say attack at UK Parliament being treated as “terrorist incident until we know otherwise.”
— BBC Breaking News (@BBCBreaking) March 22, 2017
Liz WheelerVerified account @Liz_Wheeler tweeted: “The “incidents” around UK parliament don’t sound like “incidents” to me. They sound like attacks. An 8 inch knife & a car mowing down people.”
RT UKVerified account @RTUKnews tweet reported that the House of Common suspended all of today’s debates after terrorist incident at the Parliament, and members of parliament are still in lockdown.