British police say they are investigating a “network” over the Manchester suicide bombing that killed 22 people.
"I think it's very clear that this is a network that we are investigating," Ian Hopkins, head of Greater Manchester Police said on May 24, adding that police were carrying out "extensive searches" across Manchester.
The attack at a pop concert in Manchester that killed 22 people, some of them children, may have been the work of more than one person, British Interior Minister Amber Rudd said.
"It was more sophisticated than some of the attacks we've seen before, and it seems likely -- possible -- that he wasn't doing this on his own," Rudd told BBC radio on May 24.
Rudd also said it appeared that the bomber, identified by the police as British-born Salman Abedi, 22, had recently returned from Libya. Abedi was of Libyan descent.
"Yes, I believe that has been confirmed. When this operation is over, we will want to look at his background and what happened, how he became radicalized, and what support he might have been given," she said.
Meanwhile, French Interior Minister Gerard Collomb said that Abedi is believed to have traveled to Syria and had "proven" links with the extremist group Islamic State (IS).
IS has claimed responsibility for the May 22 attack, saying it targeted "crusaders" and was carried out by "one of the caliphate's soldiers" -- wording that leaves the extent of the perpetrator's alleged ties with the group unclear.
Rudd said she was "not surprised at all" that IS claimed responsibility for the attack, but that there was no information yet to confirm the extremist organization's active direction.
Prime Minister Theresa May said on May 23 that initial investigations had "revealed that it is a possibility we cannot ignore that there is a wider group of individuals linked to this attack."
Britain's national terror threat level was raised late on May 23 to "critical," meaning another attack may be imminent.
Rudd said that up to 3,800 military personnel would be deployed on Britain's streets following the bombing, which was carried out as concertgoers -- many of them teenagers and younger children -- were leaving a show by U.S. pop singer Ariana Grande.
London police said on May 24 they would be calling in the army to help guard key landmarks, including Buckingham Palace, the Houses of Parliament, and foreign embassies.
The last time British troops were deployed on the streets was after an airliner plot in 2007.
The attack was the deadliest in Britain since July 7, 2005, when four suicide bombers attacked London's transport system during rush hour, killing 52 people.
Authorities have named five of the victims killed in the May 22 attack, which has drawn particular international condemnation because children were targeted.
The victims included 8-year-old Saffie Rose Roussos; Olivia Campbell, 15; John Atkinson, 28; Georgina Callander, thought to have been 18; and Kelly Brewster.
A Polish couple living in Britain were confirmed among the dead.
A British health official said on May 24 that about 20 people remained in critical condition.
"We are now treating 64 individuals. ... Of those, approximately 20 are receiving critical care. That means very urgent care," Jon Rouse, chief officer for health and social care services in the greater Manchester area, told Sky News.
"There is damage to major organs, major injuries in terms of limbs, and some of these individuals are going to need very long-term care and support. These are highly traumatic injuries," he said.
Authorities had earlier said that 59 people were taken to hospitals, many with life-threatening injuries, and that 12 of them were under 16 years old.
Late on May 23, thousands of people gathered at Albert Square in central Manchester to mourn the dead, a display of defiance and solidarity in the face of the attack and the persistent threat.
"The spirit of Manchester and the spirit of Britain is far mightier than the sick plots of depraved terrorists," May said in London on May 23. "That is why the terrorists will never win, and we will prevail."
With reporting by Reuters, AP, AFP, dpa, and BBC