The man who killed four people and injured dozens more in an attack outside the British Parliament before being shot to death by police was "a peripheral figure" in British terrorism investigations who had a long criminal history that included violent crimes, authorities said Thursday.
The Islamic State group claimed the British-born suspect, identified as
He is believed to be the assailant who plowed through pedestrians in a car on Westminster Bridge on Wednesday, then ran toward the Parliament compound with a knife, which he used to fatally wound a police officer before he was shot and killed by other police.
A 75-year-old man injured in the rampage died Thursday, police said, bringing the death toll to five, including the police officer and Masood. Dozens of others were injured, some seriously. Among the dead was a Utah man celebrating his 25th wedding anniversary with his wife.
The attack came one year to the day after a pair of suicide bombings in Brussels killed 32 people and injured more than 300 others. Islamic State also claimed responsibility for those attacks.
With Europe on high alert Thursday, police in Belgium said they had arrested a French man of North African descent on suspicion of attempting to run over pedestrians in a crowded shopping street in the city of Antwerp.
Soldiers on a routine patrol spotted the vehicle as it sped through the area but were unable to halt it, they said. Police were alerted and sent a rapid response team, which intercepted the vehicle and driver.
No injuries were reported, but a rifle, several knives and a canister containing an unidentified liquid were found in the vehicle, prosecutors said.
"We are monitoring the situation very closely," the Belgian prime minister, Charles Michel, said in a tweet.
French President Francois Hollande told reporters that the suspect — identified only as 39-year-old Mohamed R. — was "trying to kill or at the very least create a dramatic event." "We must therefore be extremely vigilant and also mobilize all our forces," he said.
Authorities in Britain said Masood, the London suspect, had recently been living in the West Midlands in central England, was known by several aliases and had previously been investigated by the MI5, Britain's domestic intelligence agency. He had a range of previous convictions for assaults, including grievous bodily harm, possession of offensive weapons and public order offenses dating from November 1983 to December 2003, police said. He had not been convicted of any terrorism-related offenses and was not the subject of any current police investigation.
British Prime Minister
"He was a peripheral figure," she said. "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 Islamic State-linked Aamaq news agency issued a statement saying the person who carried out the attack "was a soldier of the Islamic State."
It added that the person "carried out the operation in response to calls for targeting citizens of the coalition."
Islamic State has called on its supporters to carry out attacks against citizens of the U.S.-led coalition that has been targeting the group since 2014.
The group has been directly responsible for numerous bloody assaults around the globe but also has claimed other attacks in an apparent show of opportunism.
The assailant appeared to have acted alone but was inspired by Islamist-related international terrorism, said Mark Rowley, acting deputy commissioner at London's Metropolitan Police.
Police investigating the attack raided six addresses overnight, resulting in eight arrests. Sealed boxes of evidence were removed from the properties.
Police patrols will be stepped up in the coming days but the threat level — which was already set at severe — will not be raised and there was no information to suggest there were further threats to the public, police said.
May said that the best possible response was for the public to go about its usual routine, and that included her decision for Parliament to meet Thursday morning.
"Our values will prevail," she said.
Hundreds of people gathered for a vigil Thursday evening in Trafalgar Square to show their respect for the dead and injured.
Speeches were given by Home Secretary Amber Rudd and London Mayor Sadiq Khan, who both paid tribute to the slain police officer Keith Palmer as the crowds broke into spontaneous applause.
"He was courageous, he was brave," Rudd said. "And he was also doing his duty."
Khan condemned the "evil and twisted individuals" who seek to do harm and threaten western society's way of life.
He said London would never be cowed by terrorism and coming together Thursday night was a way to prove that.
People who gathered on a cold evening brought candles, flowers and handmade signs saying "We stand together" and "We are not afraid."
Several groups of young Muslims stood amid the crowd, eager to defend their religion as peaceful and show that they are Londoners too, and feel the pain of the attack.
"Personally, it's very difficult to see our religion put in such a bad light," said law student Naveed Mirza, 20. He and his friends were wearing T-shirts with the logo #IAmAMuslim across their chest. "But through our actions and good will we will prove to the world that Islam is a peaceful and loving religion."
Hundreds of people mingled around the square after the official vigil ended to share words with strangers. Many approached some of the Muslims present to share their respective feelings of sadness, confusion and anger at the senseless violence.
"People have got to show their support for one another," said Brian Morris, 71. "I think the average Londoner realizes that these people are radicalized maniacs, for want of a better word, who have nothing really to do with the true meaning of Islam."
"They can't beat us and they never will. We fought two world wars and won. A few terrorists are not going to overpower us."
One victim of the attack was named by British media as Spanish teacher Aysha Frade, 43, a mother of two who was on her way to collect her children from school when she was killed.
The Utah victim was identified as Kurt Cochran, who was with his wife, Melissa, who was seriously injured, according to a statement released by the Church of Jesus Christ of Latter-day Saints on behalf of Melissa Cochran's family.
Metropolitan Police announced the death of the 75-year-old victim late Thursday evening, but did not identify him.
May paid tribute to Palmer, the police officer, as a husband and father who had "devoted his life to the service of his country."
He was unarmed and standing guard in a courtyard that is not accessible to the public and leads directly into the Houses of Parliament, when the attacker approached him with a large knife and stabbed him several times.
The assailant was then shot dead by police.
"He was every inch a hero and his actions will never be forgotten," the prime minister said of Palmer.
The Palmer family issued a statement calling the slain officer "brave and courageous," "a friend to everyone who knew him" and a staunch supporter of "Charlton F.C.," a professional soccer team in southeast London.
The team issued a statement paying tribute to Palmer, with a photo of his seat — he was a season ticket-holder -- draped in the team's red scarf.
A total of 29 people were hospitalized after the attack, seven of whom remained in critical condition Thursday, police said. There were also an unspecified number of "walking wounded."
The injured include 12 Britons, as well as citizens from France, Romania, South Korea, Poland, Ireland, China, Italy, the U.S and Greece, the prime minister said.
Three police officers returning from a commendation ceremony were also hurt; two remain in a critical condition.