A 23-year-old man has been arrested in connection with the bomb attack which killed 22 people, including children, and injured 59 more in Manchester.
The arrest was announced just moments after Prime Minister Theresa May denounced the 'appalling sickening cowardice' of the lone suicide bomber who detonated a homemade device in the foyer of the Manchester Arena just as thousands of young people were leaving a concert by US pop star Ariana Grande.
Declaring that police and security services would be given whatever resources were needed to track down any accomplices of the attacker, Mrs May vowed: 'The terrorists will never win and our values, our country and our way of life will always prevail.'
Greater Manchester Police said in a statement: 'With regards to the ongoing investigation into last night's horrific attack at the Manchester Arena, we can confirm we have arrested a 23-year-old man in South Manchester.'
Speaking outside Downing Street after chairing a meeting of the Government's Cobra emergency committee, Mrs May said that police and security services believed they knew the identify of the bomber, who died alongside his victims.
She said that he had chosen the time and place of his attack deliberately to cause 'maximum carnage and to kill and injure indiscriminately'.
Mrs May, who was later travelling to Manchester to speak to police chiefs, paid tributes to emergency workers and members of the public who rushed to help.
She said they had shown: 'The spirit of Manchester and the spirit of Britain - a spirit that through years of conflict and terrorism has never been broken and will never be broken.'
Police were called to reports of an explosion at the Manchester Arena at 10.33pm, shortly after Grande had finished her performance.
Victims described being thrown by the blast that scattered nuts and bolts across the floor.
More than 240 calls were made to the emergency services, with responders including 60 ambulances flooding the area.
More than 400 police officers were deployed as part of the operation, with a visible presence remaining on the streets of Manchester on Tuesday.
The dozens of victims injured in the attack are being treated at hospitals across Greater Manchester, and a hotline has been set up for those with concerns over loved ones who remain unaccounted for.
A large cordon remains in place around the arena and nearby Manchester Victoria Station, which was evacuated during the incident and remains closed, while forensic investigators gather evidence.
Police have appealed for concert-goers and witnesses to provide police with footage from the scene if they believe it can assist the probe.