U.K. police arrest 10 in London attack probe

LONDON — British police are combing through “massive amounts of computer data,” have searched more than 20 sites and have contacted thousands of witnesses in a vast operation to trace how a British man became radicalized and launched a deadly attack on Parliament, a senior official said Friday.

In a briefing outside Scotland Yard, London’s top counterterror officer, Mark Rowley, said more “significant” arrests had been made, bringing to 10 the number of people in custody over Wednesday’s attack, which killed four people and the assailant.

Police said the attacker, Khalid Masood, was born Adrian Russell Ajao in southern England in 1964. He was also known as Adrian Elms and “may also be known by a number of other names,” police said.

The latest arrests were a man and a woman detained early Friday in Manchester, northwest England. Police believe Masood acted alone but Rowley said police were trying to determine whether others “encouraged, supported or directed him.”

The Islamic State group has claimed responsibility for the attack on Westminster Bridge and at Parliament.

Detectives have searched 21 properties in London, Brighton, Wales, Manchester and the central English city of Birmingham in one of Britain’s biggest counterterrorism operations in years. Wednesday’s attack was the deadliest in Britain since suicide bombers killed 52 commuters on London’s transit system in July 2005.

“We’ve seized 2,700 items from these searches, including massive amounts of computer data for us to work through,” Rowley said, adding that contact had been made with 3,500 witnesses.

“We’ve received hundreds of uploads of video images to our online platform. Given this attack was in the heart of the capital we also, of course, are dealing with statements from a wide range of nationalities.”

Masood drove his car into crowds on Westminster Bridge before fatally stabbing a police officer on Parliament grounds. He was shot dead by police.

An American man from Utah, a British retiree and British female school administrator were killed on the bridge, and police officer Keith Palmer was stabbed to death at Parliament, police said.

The latest victim, a man who died in a hospital Thursday, was identified as 75-year-old Leslie Rhodes from south London.

More than 50 people of a dozen nationalities were wounded in the attack, 31 of whom required hospital treatment.

“Those affected include a real cross-section of ages from at least 12 nationalities,” Rowley said. “It’s a poignant reminder, I think, that the impact of this attack on the capital will reach around the world.”

Rowley said two police officers targeted in the attack have significant injuries. Two other people also remain in critical condition, one with life-threatening injuries.