On 22 March 2017 a terrorist attack took place in the vicinity of the Palace of Westminster in London, seat of the British Parliament. The attacker, 52-year-old Briton Khalid Masood, drove a car into pedestrians on the pavement along the south side of Westminster Bridge and Bridge Street, injuring more than 50 people, four of them fatally. After the car was crashed into the perimeter fence of the Palace grounds, Masood abandoned it and ran into New Palace Yard where he fatally stabbed an unarmed police officer. He was then shot by an armed police officer and died at the scene.

Police treated the attack as "Islamist-related terrorism". Masood reportedly said in a final text message that he was waging jihad in revenge for Western military action in Muslim countries in the Middle East. Amaq News Agency, which is linked to Islamic State, said the attacker answered the group's calls to target citizens of states that are fighting against it, though the claim was questioned by the UK police and government. Police have found no link with any terrorist organisation