2017 Westminster attack

On 22 March 2017, a terrorist attack occurred outside the Palace of Westminster in London. Khalid Masood, a 52-year-old Briton, drove a hired grey Hyundai Tucson at speeds up to 76 mph into pedestrians along the south side of Westminster Bridge and Bridge Street, injuring more than 50 people and killing four. One victim, a Romanian tourist, was thrown from the bridge into the River Thames; she was rescued but later died in hospital on 6 April after her life support was withdrawn. Masood then crashed the car into the perimeter fence of the Palace of Westminster, got out, and ran into New Palace Yard, where he fatally stabbed unarmed police officer PC Keith Palmer. An armed police officer then shot Masood, who died at the scene. The entire attack lasted 82 seconds.

Of the five people killed by Masood, three were British nationals, including a teacher believed to have been walking to collect her children from school, a 75-year-old man from Clapham who died after his life support was switched off, and PC Palmer. A tourist from the United States, visiting London to celebrate his 25th wedding anniversary, also died. Around 50 other people were injured, some with catastrophic injuries, and were treated at multiple London hospitals including St Thomas' Hospital and King's College Hospital.

Police treated the attack as "Islamist-related terrorism." Investigators later recovered a final WhatsApp message from Masood stating he was waging jihad in revenge for Western military action in Muslim countries in the Middle East. The Islamic State-linked Amaq News Agency claimed Masood was a "soldier" acting on the group's calls to target coalition nations, but this claim was questioned by the Home Secretary and UK police, and investigators found no evidence linking Masood to Islamic State or al-Qaeda. On 25 March 2017, Metropolitan Police Deputy Assistant Commissioner Neil Basu announced that investigators believed Masood had acted alone.

In the days after the attack, police carried out raids across London and Birmingham as part of an investigation named Operation Classific, arresting twelve people on suspicion of preparing terrorist acts; all twelve were subsequently released without charge by 1 April 2017.

An inquest into Masood's death, held under Chief Coroner Mark Lucraft, concluded on 12 October 2018 that Masood had been lawfully killed by a minister's close protection officer, identified only as SA74, who told the court he had fired after Masood ignored warnings and ran towards him brandishing a knife.

The attack prompted a range of official and public responses, including a minute's silence in Parliament, a candlelit vigil in Trafalgar Square, and posthumous honours for PC Palmer, who was awarded the George Medal in the 2017 Queen's Birthday Honours. A memorial service and plaque were installed on Westminster Bridge on the fifth anniversary of the attack in March 2022.