Scenes from the UK Parliament attack

The U.K. Parliament is on lockdown after an assailant stabbed a police officer before being shot by police. The UK House of Commons sitting was suspended as witnesses reported gunfire outside. First responders are on the scene tending to a number of people who witnesses say were run over by a vehicle. Police continue to sweep the area and have launched a terror investigation into the incident.

People leave after being evacuated from the Houses of Parliament in central London during an emergency incident.

Armed police walk past emergency services attending to a man on the floor (top) and a police officer (centre right) outside the Palace of Westminster, London, after a policeman was stabbed and his apparent attacker shot by officers in a major security incident at the Houses of Parliament.

An injured woman is assisted after an incident on Westminster Bridge in London.

Armed police respond outside Parliament during an incident on Westminster Bridge.

An Air Ambulance on the scene after gunfire echoed close to the Houses of Parliament, London.

A medic is seen near Westminster Bridge and the Houses of Parliament on March 22, 2017, in London, England.

Armed police officers carry their weapons as forensics officers work near a grey vehicle that crashed into the railings of the Houses of Parliament in central London.

Parliament Square is under a complete security lockdown with all entrances and exits suspended, with all roads into the square cordoned off by police.

Assistant Commissioner Mark Rowley speaks of the Metropolitan Police makes a statement outside of New Scotland Yard. A police officer has been stabbed near to the British Parliament and the alleged assailant shot by armed police. Scotland Yard report they have been called to an incident on Westminster Bridge where several people have been injured by a car.

The sun sets behind the Houses of Parliament after an attack on Westminster Bridge in London.