British police on Thursday identified the lone attacker accused of carrying out a deadly knife and vehicle rampage as Khalid Masood, a 52-year-old British citizen who had a criminal record but was not suspected of plotting to “mount a terrorist attack.”

In a statement, Scotland Yard said Masood was not the subject of any current investigations and had not been convicted of any terrorism offenses before, police say, he unleashed Wednesday’s bloodshed.

The attack was one of a growing number in the West that rely on relatively low-tech, unsophisticated tools — such as a vehicle or knife — to inflict terror. The setting of Masood’s attack — some of London’s most iconic buildings dominated the scene — also meant that it had high visual impact.

“These are plots that are very easy to construct, require little money, planning and expertise, but which are nonetheless highly effective in causing death and destruction,” said Shiraz Maher, deputy director of International Center for the Study of Radicalization at King’s College London.

The attack left three people dead in central London — an American man and a British woman mowed down by a vehicle on the Westminster Bridge and a police officer stabbed outside Parliament — before the suspect was fatally shot by police. A 75-year-old man who was injured in the attack died Thursday. At least 28 people were injured, seven of them critically.

(Jason Aldag,Victoria Walker/The Washington Post)

Scotland Yard said Masood was “known to police” and had a range of previous convictions for assaults, possession of offensive weapons and public-order offenses. His last conviction was in December 2003 for possession of a knife.

“There was no prior intelligence about his intent to mount a terrorist attack,” Scotland Yard said. It said Masood was born in Kent, southeast of London, but was thought to be living in the West Midlands. He “was also known by a number of aliases,” the police said, but gave no other details about him or his family background.

Police later confirmed the identity of the American victim: Kurt Cochran, 54, of Utah. He was in London to celebrate his 25th wedding anniversary with his wife, who was injured in the attack.

Scotland Yard also announced that eight people, five men and three women, were arrested Wednesday night and Thursday morning in connection with the case. They were picked up “on suspicion of preparation of terrorist acts” and ranged in age from 21 to 58, police said.

Earlier Thursday, British Prime Minister Theresa May said the attacker was once investigated by Britain’s MI5 security service for possible extremist links but was “not part of the current intelligence picture.”

May did not name the assailant in her remarks, but she offered new details about past scrutiny by authorities, who described the London attacks as “inspired by international terrorism.”

Shortly after May spoke, the Islamic State-linked news site Amaq carried a statement calling the attacker a “soldier” of the group’s self-proclaimed caliphate. British authorities have announced no links between the suspect and the Islamic State, but the militant group has often independently asserted ties to attacks around the world.

1 of 47 Full Screen Autoplay Close Skip Ad × The scene of the shooting incident outside London’s Houses of Parliament View Photos Police respond to reports of shooting in London. Caption An assailant plowed a vehicle through a crowd of pedestrians and then fatally stabbed a police officer. March 23, 2017 British Prime Minister Theresa May speaks in the Houses of Parliament following the attack in London. PA via AP Buy Photo Wait 1 second to continue.

Across the English Channel in Antwerp, Belgium, authorities were placed on high alert after a man tried to drive a car carrying weapons, including a gun, into a pedestrian zone.

Belgian police said the car, with French license plates, sped onto the street, forcing people to jump out of the way. Belgian federal prosecutor Eric Van der Sijpt identified the driver as a French citizen, Mohamed R., 39, and said a long knife, gun and container containing an unidentified substance were found in the trunk. Further details were not immediately available, but the case was referred to Belgian federal prosecutors, who handle militant attacks or threats.

In her statement to the House of Commons, May said that the London assailant was born in Britain and was investigated by security services “some years ago . . . in relation to concerns about violent extremism.”

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“He was a peripheral figure,” she added. “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. Intensive investigations continue.”

A spokesman for the Enterprise rental car company confirmed reports that the Hyundai i40 used in the attack came from one of its branches in Birmingham, which is in the West Midlands.

A minute’s silence was observed in Parliament, Scotland Yard and London’s City Hall to honor the lives lost in the attack. The observance took place at 9:33 a.m. in tribute to slain police Officer Keith Palmer, who wore the shoulder number 933 on his uniform.

Investigators conducted raids linked to the investigation, including in London, Brighton, Wales and Birmingham. About a mile away from the rental company in Birmingham, police guarded the entrance to the apartment building where one of the raids took place.

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The attack carried hallmarks of strikes last year in Nice and Berlin, where vehicles were used as tools of terrorism.

The assailant first plowed the Hyundai through terrified pedestrians along the bridge, killing at least two people: Aysha Frade, a 43-year-old mother of two, who was reportedly walking on Westminster Bridge on her way to pick up her children; and Cochran, the American who was visiting with his wife, Melissa, to celebrate their anniversary. No details about the 75-year-old man were immediately known.

In a Twitter post, President Trump shared “prayers and condolences” with Cochran’s family and friends.

The injured represented a wide range of nationalities: British, French, Romanian, South Korean, Greek, German, Polish, Irish, Chinese, Italian and American.

One Romanian woman who was walking along Westminster Bridge plunged into the Thames but was pulled alive from the river.

British Foreign Minister Boris Johnson said the international scope of the casualties “goes to show, an attack on London is an attack on the world.”

Murphy reported from Washington. Adam Taylor and Isaac Stanley-Becker in London, Rick Noack in Birmingham, Griff Witte in Madrid, Michael Birnbaum and Annabell van den Berghe in Brussels, and William Branigin, Carol Morello and Mark Berman in Washington contributed to this report.

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