London: A day after a terror attack in the heart of London left four people dead, police on Thursday identified the lone attacker as a British-born and said eight suspects had been arrested.
Seven of the persons wounded in the Wednesday attack near Parliament were in critical condition, authorities said. Twenty-nine were discharged from hospitals.
The Islamic State claimed responsibility for the attack. It said the attacker was "a soldier ... executing the operation in response to calls to target citizens of coalition nations".
Mark Rowley, Acting Deputy Commissioner and head of Counter-Terrorism unit, said the dead included Aysha Frade, a woman who worked at a London college, an unnamed man in his 50s, police officer Keith Palmer and the attacker himself.
At least 40 people were hit on the iconic and crowded Westminster Bridge when the attacker drove a car along the pavement, knocking down unsuspecting pedestrians before crashing into a fence below Big Ben.
He then stabbed the unarmed Palmer on the grounds of Parliament before being shot dead.
Speaking in Parliament, Prime Minister Theresa May said the attacker was investigated some years ago over violent extremism but had been a "peripheral figure".
"He was not part of the current intelligence picture," she said.
May paid tribute to Palmer: "He was every inch a hero and his actions will never be forgotten."
She told MPs, many of whom had been caught up in the commotion: "We will never waver in the face of terrorism."
Rowley said hundreds of detectives worked through the night and searched six addresses, the BBC reported. Inquiries were held in London, Birmingham and other parts of the country.
"This attacker was inspired by international terrorism ... Islamist terrorism," Rowley said.
May said 12 Britons were admitted to hospital. Other victims included four South Koreans, three French children, two Romanians and Greeks each and one each German, Pole, Irish, Chinese, Italian and American.
One woman fell into the Thames from the bridge but was alive.
Indian President Pranab Mukherjee and Prime Minister Narendra Modi on Thursday joined world leaders to denounce the killings.
Mukherjee said India stood by the United Kingdom and that "terrorism must be met through collective action by the international community".
Modi added: "Deeply saddened... Our thoughts and prayers are with the victims and their families. At this difficult moment India stands with the UK in the fight against terrorism."
Flags were lowered to half mast over Downing Street.
The US, France and the European Union strongly condemned the attack.
President Donald Trump spoke with Theresa May and applauded the quick response of British authorities.
Witness Jayne Wilkinson said: "We were taking photos of Big Ben and we saw all the people running towards us. Then there was an Asian guy in about his 40s carrying a knife about seven or eight inches long.
"And then there were three shots fired, and then we crossed the road and looked over. The man was on the floor with blood.
According to Rowley, more police officers would be deployed on the streets of London. Officers' leave have been cancelled and duty hours extended.
Defence Secretary Sir Michael Fallon said the security at Parliament would be reviewed.
MPs held a minute's silence before Parliament continued business as normal.
Asked about the mood of the city, Fallon said: "London is getting back to normal. They've seen terrorism like this before and they are not going to let it triumph."