MANCHESTER, England â The police chief leading the investigation into a suicide bombing that killed 22 people at a Manchester concert said Wednesday that the attacker did not act alone and that authorities are trying to unravelÂ a wider web of plotters.
âItâs very clear that this is a network we are investigating,â said Greater Manchester Chief Constable Ian Hopkins.
The comments â which came as British troops fanned out across London at prominent sites such as 10 Downing Street and Buckingham Palace â confirmed what other senior British officials have hinted. They also offered further insights into Britainâs decision to raise the nationâs threat level to its highest point.
In Libya, meanwhile, an official said counterterrorism authorities have arrested at least two members of the family of the bomber, Salman Abedi, including a younger brother suspected of planning an attack in Libyaâs main city, Tripoli. The bomber was a British-born citizen whose parents emigrated from Libya.
Ahmed Dagdoug, spokesman for Libyaâs counterterrorism Reda Force, said Hashem Abedi was arrested Tuesday and is suspected of âplanning to stage an attack in Tripoli.â Abediâs father, Ramadan, was arrested Wednesday.
Dagdoug said Hashem was also in frequent contact with his brother Salman in Manchester and was aware of the plans to attack the concert.
It was unclear whether Abediâs relatives were a key part of the network planning the Manchester attack, but authorities were increasingly exploring the emerging connections between Britain and Libya.
In Britain, Hopkins said British police have taken at least five people into custody in connection with the attack.
Raids continued Wednesday in Britain, including one in the heart of Manchester â not far from the concert venue where Salman Abedi detonated the blast that claimed victims as young as 8 years old.
Britainâs domestic security chief, Home Secretary Amber Rudd, told the BBC that security services â which had been aware of Abedi âup to a pointâ beforeÂ the bombing â were focusing on his visits to Libya, at least one of which was very recent.Â
Ruddâs French counterpart, Interior Minister Gerard Collomb, told broadcasterÂ BFM TV that Abedi may have also gone to Syria and hadÂ âprovenâ links with the Islamic State, which claimed responsibility for the Manchester blast and called Abedi a âsoldier.â
Abediâs father, Ramadan Abedi, said his son sounded ânormalâ when they last spoke five days ago. Before his arrest, the elder Abedi told the Associated Press by telephone from Tripoli that his son planned to visit Saudi Arabia and then spend the Islamic holy month of Ramadan with family in Libya.
âWe donât believe in killing innocents,â he told the AP. âThis is not us.â
The local mosque where Salman Abediâs family worshiped â and where Ramadan Abedi had once worked, issuing the call to prayer â denounced the attack. Mosque officials also denied reports that the bomber had worked there.Â
âThe horrific atrocity that occurred in Manchester on Monday night has shocked us all,â said Fawzi Haffar, a trustee with the Manchester Islamic Center, also known as the Didsbury Mosque.Â âThis act of cowardice has no place in our religion, or any other religion.âÂ
Salman Abedi was described in reports Wednesday as a college dropout who had recently become radicalized. Security experts said it was unlikely that he coordinated the attack, and the BBC reported he may have beenÂ âa muleâ tasked with carrying out the bombing but who had little role in creating the explosive or choosing the target.
Of particular concern to British investigators was the possibility that the bombmaker was still at large and may be planning to strike again.
On Tuesday night, British Prime Minister Theresa May took Britainâs alert level fromÂ âsevereâ to its highest rating, âcritical.â The decision, she said, was âa proportionate and sensible response to the threat that our security experts judge we face.â
The impact was quick and visible.
In London, nearly 1,000 soldiers were deployed onto the streets to help free up police. Soldiers were seen at prominent locations, including Downing Street and Buckingham Palace.
Hopkins said there were no plans to deploy troops in Manchester. But armed police officers were more visible on the cityâs streets Wednesday than usual, and Hopkins said the deployment of soldiers in the capital would make more police available in other parts of the country.
The British Parliament announced that âdue to the raised national security threat,â all public tours of the Palace of Westminster would be stopped. The changing of the guard ceremony at Buckingham Palace â a popular tourist attraction â was also canceled.
American pop star Ariana Grande, who had just finished performing when the Manchester concert venue was bombed, announced the cancellation of concerts in London on Thursday and Friday out of respect for the victims.
Chelsea, the title-winning soccer club in Englandâs Premier League, called off a planned victory parade through London in an open-top bus. The team said in a statement that it âwould not want in any way to divert important resources.â
âItâs a very good thing. Itâs visibility, itâs assurance,â said Geanalain Jonik, a 48-year-old tourist from Paris who was peering through the railings of Buckingham Palace.
A similar military presence has brought reassurance in Paris since attacks in 2015, he said. âWe donât have enough policeman, and when you see soldiers and troops in the streets, itâs better,â he added. âIt gives you the sense of feeling safe.â
Health officials said Wednesday that in addition to the dead, 20 people remained inÂ âcritical careâ and were suffering fromÂ âhorrific injuries.â
After years of successfully fending off more-sophisticated strikes even as countries across continental Europe have fallen victim to bombings, Monday nightâs carnage underscored that Britain is not immune amid a rising tide of extremist violence.Â
âGetting a car or a knife is easy,â said Raffaello Pantucci, a terrorism expert at the London-based Royal United Services Institute. âMaking a bomb that works and goes off when you want it to go off takes preparation and practice. And it usually involves other people.â
Pantucci said British authorities âare going to try to figure out who [Abedi] knows, who heâs linked to. Did he build the bomb itself, or did someone build it and give it to him?â
A family friend said Abedi traveled frequently between Libya and Britain. âWe have a Daesh problem in Libya. We wonder whether he met people there who trained him,â said the friend, who spoke on the condition of anonymity. Daesh is an Arabic acronym for the Islamic State.
Even before Mayâs announcement of a âcriticalâ threat level for just the third time â the first two came in 2006 and 2007 â authorities from London to Scotland said they would be reviewing security plans for upcoming public events. Smaller gatherings that would not have been policed in the past may now get protection, they said.
âOver the coming days as you go to a music venue, go shopping, travel to work or head off to the fantastic sporting events, you will see more officers, including armed officers,â saidÂ Commander Jane Connors of Londonâs Metropolitan Police Department.
Mayâs decision to deploy the military means the public may now see soldiers rather than police. May said the military would operate under police command.
The escalation came as the nation grieved for the young victims, with thousands of people converging on Manchesterâs graceful Albert Square for a vigil that was part solemn remembrance and part rally against extremism.
To roaring applause, Manchester Mayor Andy Burnham vowed that the city â which has seen hardship, having been bombed relentlessly during World War II â would not succumb to division or anger.Â A poet named Tony Walsh delivered an ode to the city titled âThis is the Place.â And in what has become a dark mainstay of life in Western Europe, passersby left candles, flowers and cards for the dead.Â
The casualties included children as young as elementary school students. Police said that among the 59 people injured, a dozen were younger than 16.Â Among the dead was Saffie Rose Roussos, who was just 8 years old.Â
Hopkins said Wednesday that an off-duty police officer was also killed and that medical examiners had finished identifying the victims.
In a speech outside 10 Downing Street, where flags were lowered to half-staff, May called the Manchester killings a âcallous terrorist attack.âÂ
âThis attack stands out for its appalling, sickening cowardice deliberately targeting innocent, defenseless children and young people who should have been enjoying one of the most memorable nights of their lives,â she said.
The attack was the worst terrorist strike on British soil since 2005, when Islamist extremists bombed the London subway and a bus,Â killing 52 people.
Pantucci, the security expert, said that authorities had disrupted several plots in recent months but that Mondayâs attack somehow slipped through. Understanding why, he said, will be crucial.
âTheyâve been dealing with a very high threat tempo,â he said. âBut this is one they werenât able to stop.âÂ
And in a highly unusual public rebuke, Rudd, the home secretary, slapped down U.S. authorities for leaking information about the investigation.Â
Some details about the case â including the suspectâs name â first appeared in U.S. media.
When asked by the BBC whether she would look again at information-sharing with other countries, she said: âYes, quite frankly. The British police have been very clear that they want to control the flow of information in order to protect operational integrity, the element of surprise.âÂ
She said it was âirritating if it gets released from other sources, and I have been very clear with our friends that should not happen again.â
Adam reported from London, and Raghavan from Tripoli, Libya. Souad Mekhennet, Isaac Stanley-Becker, James McAuley and Rick Noack in Manchester; Paul Schemm in Addis Ababa, EthiÂoÂpia; and Devlin Barrett, Brian Murphy and Ellen Nakashima in Washington contributed to this report.