"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," police said in a statement.
This is Britain's deadliest terror attack in 12 years. The man behind Monday's terror attack at singer Ariana Grande's concert in north England's Manchester city died when he detonated his device, killing 22 others, including children and injuring 59 people, police said.
Screaming fans, including many teenagers, fled the venue in panic after the bomb blast at the end of the concert as their parents waited in anguish.
"The arena was scarily still for five or six seconds, which felt like a lot longer, and then everybody just ran everywhere," Kennedy Hill, a teenager at the concert, told AFP.
"There were fathers carrying their little girls in tears," said Sebastian Diaz, a 19-year-old from Newcastle.
Ambulances and bomb disposal teams rushed to the venue, as family members frantically searched for their loved ones, and residents opened their doors to stranded concert-goers after trains were cancelled.
British Prime Minister Theresa May condemned the "appalling terrorist attack" and suspended her campaign for the general election on June 8 along with chief opposition leader Jeremy Corbyn.