How the Manchester Arena attack unfolded (all times GMT):
6pm – Doors open at Manchester Arena in the north of the city centre. US pop singer Ariana Grande is on the bill for a sell-out concert. Fans, many of them teenage girls, wait for the show to begin.
7.30pm – Show’s scheduled start time. After a performance from support act BIA, an American rapper, Grande takes the stage.
10.30pm – Show’s scheduled finish. Thousands of fans begin to file out of the arena’s four exits.
A “huge bomb-like bang” is heard at the arena.
Witnesses describe being knocked from their feet by an explosion and seeing dozens of injured, possibly dead, people including children lying on the floor.
10.33pm – Greater Manchester Police (GMP) are called to reports of an explosion at Manchester Arena.
10.55pm – Police urge people to stay away from the area as responders deal with a “serious incident”.
1.10am – Nineteen people are confirmed dead and about 50 others injured following the explosion police say is being treated as a terrorist incident.
1.35am – A controlled explosion is carried out on a suspicious item in the Cathedral Gardens area near Manchester Arena. It is later confirmed to be abandoned clothing.
2.15am – Prime Minister Theresa May says her thoughts are with the victims and families of those affected in “what is being treated by the police as an appalling terrorist attack”.
4am – Ariana Grande tweets that she is “broken”, adding: “From the bottom of my heart, I am so so sorry.”
7am – GMP Chief Constable Ian Hopkins says the death toll has risen to 22, including children, with 59 injured. He says police believe it was carried out by a suicide bomber detonating an improvised explosive device.
9am – US President Donald Trump expresses his “deepest condolences” and calls those responsible “evil losers”.
11am – May says the attacker has been identified by security services but does not release details.
GMP later says it has arrested a 23-year-old man in connection with the incident.
12.12pm – The Queen releases a statement expressing her “deepest sympathy” to those affected by the explosion.
1pm – Islamic State claims responsibility for the attack.
2pm – GMP say they have executed warrants at addresses in Whalley Range, and one in Fallowfield, where they carried out a controlled explosion.
5.21pm – GMP confirm the suicide bombing suspect is believed to be 22-year-old Salman Abedi.
Early evening – thousands gather for a vigil in Manchester’s Albert Square. Elsewhere, vigils attract hundreds to city centres across nation.
9.40pm – The UK’s terror threat level is increased from severe critical, indicating a further attack might be imminent.