The suicide bomber who brought carnage to the Manchester Arena has been named as Salman Abedi.
Monday night’s attack at a concert by US pop star Ariana Grande left 22 people dead, including an eight-year-old girl, and dozens injured.
Theresa May raised Britain’s terror threat level from severe to critical and said the military could be deployed to support armed police officers at public events.
Abedi, believed to have been born in Manchester and of Libyan descent, studied business at Salford University but dropped out before completing his degree.
Abedi, who was reportedly known to the security services, is thought to have returned from Libya as recently as this week.
A school friend told The Times: “He went to Libya three weeks ago and came back recently, like days ago.”
A family friend, who asked not to be named, described him as “normal” and said they were known to the Libyan community in the city.
He said: “He was always friendly, nothing to suggest (he was violent). He was normal, to be honest.”
Abedi was named after armed officers carried out a raid on the red brick semi in south Manchester where he was registered as living.
Greater Manchester Chief Constable Ian Hopkins said detectives were working to establish whether he was working alone or as part of a network.
Residents were ordered to stay inside as around 20 police swooped on a house in Elsmore Road in Fallowfield carrying out a controlled explosion on the front door.
Elsewhere in south Manchester, the first arrest was made in connection with the inquiry when a 23-year-old man was detained near a Morrisons in Chorlton.