Born in Manchester to Libyan parents, Salman Abedi was confirmed by police to be the bomber. A 23-year old that was arrested may be his brother.

The suspected suicide bomber who killed 22 people at a concert in Manchester, northern England, on Monday has been identified as 22-year-old Salman Abedi, British police said.
Abedi was born in Manchester in 1994 to parents of Libyan birth, US security officials said, citing British intelligence officials.
His parents emigrated from Libya to London before moving to the Fallowfield area of south Manchester, where they have lived for at least 10 years, the officials said.
Police raided a house in Elsmore Road in Fallowfield earlier on Tuesday.
Suspect believed to be brother
A 23-year-old man arrested by police in a separate move in south Manchester in connection with the attack on Tuesday was believed to be Abedi's brother, news reports said.
Abedi had a sister named Jomana Abedi, the U.S. security officials said.
The Guardian newspaper reported that Abedi's identity was confirmed by British police "after officials in the United States passed it to news reporters, apparently against the wishes of the police and security services in the UK".
His parents emigrated from Libya to London before moving to the Fallowfield area of south Manchester, where they have lived for at least 10 years, the officials said.
A U.S. government source said investigators were looking at whether Abedi had travelled to Libya and whether he had been in touch with Islamic State militants there.
Police raided a house in Elsmore Road in Fallowfield earlier on Tuesday.
A 23-year-old man arrested by police in a separate move in south Manchester in connection with the attack on Tuesday was believed to be Abedi's brother, news reports said.
Abedi had a sister named Jomana Abedi, the U.S. security officials said.
Abdalla Yousef, a spokesman for the Didsbury Mosque in Manchester, said Abedi's father and brother had prayed there but Abedi had worshipped at another mosque.
Family moved back to Libya
"I have managed to track down somebody who knows the family. He confirmed his father and sister and the rest of the family had moved to Libya and had moved there straight after the revolution after Gadaffi was killed," Yousef said.
He said it was possible the brothers had travelled between the two countries since then.
A trustee of the mosque, Fawzi Haffar, said Abedi's father was currently in Libya and had been there for a while.