Four people were killed and scores injured when an attacker plowed a car through crowds in central London before attempting to storm the Houses of Parliament in what police believe was an act of Islamist-inspired terrorism.
Police indicated they knew the identity of the assailant, who fatally stabbed unarmed police officer Keith Palmer, a 15-year-veteran, on the grounds of Parliament after ramming a car onto the crowded sidewalks nearby. Armed officers shot the attacker dead.
It was the first mass-casualty terrorist attack in Britain since 2005 when 52 people and four attackers died in the July 7 bomb attacks on the London public transportation system. The use of a vehicle as a weapon of terror echoed the methods used in the past year by attackers in Nice and Berlin.

The London assault, which came on the one-year anniversary of the ISIS bomb attacks in Brussels, brought carnage to Westminster, the heart of political life in Britain.
London attack part of disturbing trend
Prime Minister Theresa May described the attack as "sick and depraved." She said attempts to defeat through violence the values Parliament represents would be "doomed to failure."
"The location of this attack was no accident. The terrorist chose to strike at the heart of our capital city, where people of all nationalities, religions and cultures come together to celebrate the values of liberty, democracy and freedom of speech," she said.

Parliament was placed on lockdown for several hours and lawmakers were forced to remain in the main debating chamber of the House of Commons as officers rushed to the scene outside.
Pictures showed scenes of carnage in the aftermath of the attack, which happened as Parliament was in session. One member of the British government gave mouth-to-mouth resuscitation to the officer who died from stab wounds.

'Islamist-related'
Mark Rowley, Britain's most senior counterterror police officer, told reporters late Wednesday that authorities believe they know the attacker's identity but are not releasing it, and are operating on the assumption the incident was "Islamist-related terrorism."
"This is a day that we had planned for -- that we all hoped would never happen -- but sadly it is now a reality," said Rowley, acting deputy commissioner of the Metropolitan Police.
He said Palmer, 48, was a father and a husband.
Rowley said 40 people were hurt.