LONDON — The knife-wielding terrorist who killed an American tourist and two others outside the U.K. Parliament was British-born and previously investigated for "violent extremism."
Police identified the suspect as Khalid Masood, 52, on Thursday. Authorities said Masood was born in Kent and detectives believe he was most recently living in the West Midlands. He was known by a number of aliases, police said.
Masood was known to security services as "a peripheral figure" and "was not part of the current intelligence picture," Prime Minister Theresa May told the House of Commons on Thursday.
Police also said Masood was not the subject of any current investigations and there were no prior intelligence reports indicating his intent to carry out the terror attack.
Masood was known to police for a range of previous convictions, they said, including for assaults, possession of offensive weapons and public order offenses.
His first conviction was in 1983 for criminal damage and his most recent was in December 2003 for possession of a knife. He was never convicted of any terror-related offenses.
Kurt Cochran, who lives in Utah, was among the three slain, Church of Jesus Christ of Latter-day Saints spokesman Eric Hawkins told NBC News. His wife Melissa, whose parents are currently serving as missionaries in London, was also injured. They were celebrating their 25th wedding anniversary.
The others killed were a police officer and a mother-of-two who was hit by a bus as she ran to safety.
The terrorist plowed a 4x4 rental vehicle into people walking on Westminster Bridge before crashing it into a railing outside the House of Commons. He later fatally stabbed the cop before being gunned down by armed officers.
Police said Thursday afternoon that five people remained in critical condition after the attack, with two sustaining life-threatening injuries.
"It is still believed that this attacker acted alone and the police have no reason to believe that are imminent further attacks on the public," May said, just yards from Wednesdays carnage.
However, police overnight raided at least six properties in cities including Birmingham — where the culprits vehicle was rented from Enterprise — and London, making eight arrests.
"Clearly our investigation is ongoing … and is focused on his motivation, his preparation and associates," Metropolitan Police Acting Deputy Commissioner Mark Rowley told reporters early Thursday.
Police said later Thursday that those arrested overnight included a 39-year-old woman in east London, a 21-year-old woman and 23-year-old man in Birmingham, a 26-year-old woman and three men aged 28, 27, and 26 at a separate address in Birmingham.
An eighth person, a 58-year-old man, was arrested Thursday morning at another address in Birmingham, police said. All eight were taken into custody on suspicion of preparation of terrorist acts, police said.
A home raided in Birmingham was one where Masood lived until late last year, a neighbor told the AP. Shown a photo of him, Iwona Romek said "that is 100 percent" the man who lived next door to her for about five months.
Romek said Masood had a wife and child of about 6, and would walk the child to school. He rarely left in the evening.
"He seemed like a normal family man who liked to take care of his garden," she said. But one day she saw him packing their belongings in a black van he bought to replace a red Fiat, and then they were gone.
Amaq, the media unit of ISIS, released a statement describing the London attacker as "a soldier of the Islamic State" although it cited no evidence for the claim.
Charlie Winter, a senior research fellow at the London-based International Centre for the Study of Radicalisation and Political Violence (ICSR), said the claim framed the atrocity as inspired, not directed, by ISIS. "This distinction is hugely important," he wrote.
ISIS has claimed responsibility after other attacks, including the Istanbul nightclub rampage on New Years Eve and the Nice promenade truck massacre last July, without providing evidence.
One of the dead was identified as Aysha Frade, 43, a mother-of-two who was hit by a bus as she fled from the vehicle on Westminster Bridge. She was on her way to pick up her children from school.
The small Spanish town of Betanzos, where her family lives, declared three days of mourning.
Lawmakers observed a minutes silence in tribute to slain police Constable Keith Palmer, 48, who died despite efforts to revive him by doctors and a passing government minister.
One of the wounded was a tourist who plunged from the bridge into the River Thames. The woman, who was in the city to celebrate her boyfriends birthday, suffered serious head injuries and has badly damaged lungs, Romanian diplomat Dan Mihalache told Realitatea TV, according to The Associated Press.
May said the suspect had been investigated "some years ago" by the MI5 domestic intelligence service "in relation to concerns about violent extremism."
May added: "He was a peripheral figure. The case is historic. He was not part of the current intelligence picture. There was no prior intelligence of his intent or of the plot."
The prime minster told lawmakers that "the working assumption is that the attacker was inspired by Islamist ideology."
May also paid tribute to government minister Tobias Ellwood, who tried to save the dying police officer. "Yesterday we saw the worst of humanity but we will remember the best," she said.
Mayor Sadiq Khan invited Londoners to an evening vigil and promised "business as usual" in the capital.
"London is a city thats been resilient in the face of terror attacks in the past," he told NBC News. "People are returning to work today … were not going to allow a terrorist to divide our communities or change our way of life."
More police officers than usual were on patrol as the Metropolitan Police aimed to provide "reassurance."
Westminster Bridge remained cordoned off and the surrounding streets — normally thronged with commuters — were eerily quiet except for the buzz of a police helicopter.
Defense Minister Michael Fallon described Wednesdays atrocity as a "lone-wolf attack" but said investigators were still checking "whether other people were involved."
He added: "London is getting back to work. London has seen this before and is taking it on the chin."
As dusk fell, a silent vigil was held by several thousand people in Trafalgar Square, where the bongs of Big Ben could be heard in the distance, according to the AP.
"Those evil and tortured individuals who try to destroy our shared way of life will never succeed," Mayor Sadiq Khan told the crowd.