LONDON — Police investigating the deadliest terror attack in central London in 12 years named the perpetrator Thursday as a 52-year-old British man, Khalid Masood.
As the inquiry into the atrocity gathered pace, Prime Minister Theresa May revealed the attacker was once linked to violent extremism. He was thought to have been inspired by Islamist ideology, she said.
In an address to the House of Commons — reconvened less than a day after it was placed in lockdown as the attack unfolded outside — May vowed that Britain’s freedoms and values would remain undiminished.
Three people died in the attack. An American man and a British woman of Spanish origin were killed when Masood rammed a rental car onto the sidewalk on Westminster Bridge.
Masood then stabbed an unarmed police officer in as he stood guard at Carriage Gates, an entrance into a cobbled courtyard frequently used by Members of Parliament and staff.
An ISIS-affiliated news agency claimed that the extremist group was behind Wednesday’s outrage, which left 29 people requiring hospital treatment. Some remained critically ill on Thursday.
In a defiant speech, May vowed that Britain’s freedoms and liberties would remain undiminished.
“Yesterday an act of terrorism tried to silence our democracy. But today we meet as normal — as generations have done before us, and as future generations will continue to do — to deliver a simple message: we are not afraid. And our resolve will never waiver in the face of terrorism,” she said.
“And we meet here, in the oldest of all Parliaments, because we know that democracy — and the values it entails — will always prevail.”
She said the police officer who was killed in the attack, PC Keith Palmer, was “every inch a hero and his actions will never be forgotten.”
May said Wednesday’s attacker was born in Britain and was investigated “some years ago” in relation to concerns about “violent extremism.” But he was not part of the “current intelligence picture.”
May said the current threat level for Britain — which has been at severe, the second highest, for some time — would not be raised to critical because there was no specific intelligence that an attack was imminent.
Since 2013, police, security and intelligence agencies have successfully disrupted 13 separate terrorist plots in Britain, she said.
“We know the threat from Islamist terrorism is very real. But while the public should remain utterly vigilant they should not — and will not — be cowed by this threat,” she said.
Terrorism analyst Paul Cruickshank said the language used by ISIS asserting the attack was by one of its “soldiers” did not necessarily mean the group was claiming direct connections to the attacker.
This phrasing has been used in the past by the group for attacks ISIS believes it helped inspire, he said.
Mark Rowley, the lead officer in the UK for counter-terrorism policing, said hundreds of detectives worked through the night in a fast-moving inquiry. Their investigation focused on the attacker’s motivation, preparation and associates, he said.
“It is still our belief — which continues to be borne out by our investigation — that this attacker acted alone yesterday and was inspired by international terrorism,” he said. “To be explicit, at this stage, we have no specific information about further threats to the public.”
A U.K. official said the working theory was that the attack was ISIS “inspired or copycat,” but the authorities were “still investigating.”
“Values and community cohesion are now most important — this is kind of a test case,” he said.
A candlelit vigil will be held Thursday evening in Trafalgar Square, not far from Westminster, to show solidarity and remember the victims, the office of London Mayor Sadiq Khan said in a statement.
“London is the greatest city in the world. We will never be cowed by terrorism. We stand together, in the face of those who seek to harm us and destroy our way of life. We always have, and we always will,” it said.
Rowley told journalists late Wednesday that police believe the attack was an act of “Islamist-related terrorism,” and indicated they knew the identity of the assailant but were not releasing his name.
Overnight, police in Birmingham, in central England, raided an apartment, but it was not clear whether it was linked to the London attack.
Only one of the victims has been publicly identified. Keith Palmer, a 15-year veteran of the London police force, was fatally stabbed on the grounds of Parliament before police killed his attacker.
A number of tourists were among 40 people hurt in the assault, including five South Koreans and three French high school students, according to officials from both countries.
One Australian had been hospitalized, officials there said. A Chinese foreign ministry spokeswoman said one Chinese tourist was slightly injured.
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.
British lawmakers are returning to Parliament on Thursday, where many were trapped for hours as the police operation unfolded outside the previous day.
One member of the government, Tobias Ellwood, was lauded a hero after attempting to save the police offer, Keith Palmer, who later died.