Everything we know a day on from the Westminster attack
The attacker has been named by police as Khalid Masood.
A massive police operation is under way into the car and knife terror attack that shook the heart of London yesterday.
These are the latest developments:
What do we know about the attacker?
Scotland Yard have formally identified the man believed to be responsible for the attack as 52-year-old Khalid Masood.
The force said Masood had previous convictions for assaults, including GBH, possession of offensive weapons and public order offences. He had not been convicted of any terrorism offences.
Theresa May revealed earlier that he was British-born and was investigated by MI5 some years ago over concerns of violent extremism.
What did he do?
The attacker, armed with two large knives, drove a Hyundai 4×4 – which was hired from a branch of car hire-firm Enterprise in Shirley, Solihull – into pedestrians on Westminster Bridge.
He jumped out of the car after smashing it into the railings encircling the Palace of Westminster, fatally stabbing Pc Palmer as he entered the grounds. He was shot dead moments later by another officer.
Has anyone been arrested?
Eight people have been arrested and six addresses raided across London, Birmingham and elsewhere.
Has anyone claimed responsibility?
The so-called Islamic State group has claimed responsibility, saying through its Aaamaq news agency that the London attacker was a “soldier” of theirs.
Who were the victims?
Four people have died – the victims have been named as 48-year-old husband and father Pc Keith Palmer; mother-of-two Aysha Frade; and US tourist Kurt Cochran. The attacker also died.
Among the injured are 12 Britons, three French children, two Romanians, four South Koreans, two Greeks, and one each from Germany, Poland, Ireland, China, Italy and the United States.
Three police officers were also hurt, two of them seriously.