While investigators are still working to piece together what happened, all signs point to a suicide bomber as the culprit.
Here is a closer look at the events of the deadly blast in Manchester:
All events are reported in Greenwhich Mean Time (GMT).
MONDAY, MAY 22, 2017
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6:30 p.m.
As many as 21,000 people filled Manchester Arena for Ariana Grande's sold-out "Dangerous Woman" Tour.
10:33 p.m.
An explosion ripped through the performance hall's foyer near the ticket booths, according to Manchester Chief Constable Ian Hopkins.
Inside the arena, crowds reacted to the sound of the explosion and evacuated the building.
An unspecified number of injuries were reported.
11:52 p.m.
Manchester police confirmed "several people" died in the blast.
TUESDAY
12:16 a.m.
A representative for Grande said the singer was not injured in the explosion.
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Manchester police said a second incendiary device was found at Manchester Arena, and crews prepared a controlled explosion.
1:17 a.m.
Police said 19 people were confirmed dead and as many as 50 people were injured. Ian Hopkins said the matter was "being treated as a terrorist incident."
The second reported device at the scene of the controlled explosion was described as a pile of clothes found at the arena, police said.
Around 2 a.m.
Manchester police said they were investigating the possibility the incident was carried out by a suicide bomber.
3:59 a.m.
In the U.S., the Department of Homeland Security said there are no credible threats to music venues in America.
The department also said the public may notice increased security in and around public places and events.
5:11 a.m.
Hopkins said the death toll had rose to 22 people, and the attacker who died at the scene was carrying an IED that he detonated.
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8:45 a.m.
British Prime Minister Theresa May called an emergency meeting of COBRA, the UK cabinet department, for briefing on the investigation.
9 a.m.
Manchester police said the terror incident was being investigated by national law enforcement and intelligence agencies.
Officials announced a telephone hotline was being created to help concerned families locate their loved ones.
Around 11 a.m.
Runshaw College identified the first named victim in the concert blast as Georgina Callander, who was studying health and social care.
11:08 a.m.
Prime Minister May called the terrorist attack "among the worst Britain has experienced" and said police believe they know the identity of the bomber, but were not releasing his name.
11:53 a.m.
Police announced a 23-year-old man was arrested in South Manchester in connection with the concert attack.
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