■ Nineteen people were killed and 59 others were injured in an explosion about 10:35 p.m. on Monday in the foyer outside the main hall of the Manchester Arena.
■ Prime Minister Theresa May said the police were treating the incident as “an appalling terrorist attack.”
■ The authorities suspect the blast came from either an abandoned backpack or a suicide bomber, a senior American intelligence official said. British officials said they were investigating reports that a suicide bomber detonated an improvised device containing nuts and bolts as shrapnel.
■ The explosion occurred just as a concert by the American pop star Ariana Grande was ending. Traumatized fans, including children, screamed and ran. Ms. Grande was not injured.
■ Parents who were separated from their children during the mayhem were told to go to nearby hotels, where many had taken refuge. Other children were being kept in the arena.
■ The police carried out a controlled explosion near the arena but later said the suspicious material was harmless. Bomb squads continued to comb through downtown Manchester.
Location of the Blast
‘Everyone Started Crying and Screaming’
Laura Bruce, 18, was with her sister Amy, 25, in one of the arena’s upper tiers when they heard the explosion. “Everyone below us just turned and ran,” she said. “Because we were higher up, we could not get out for five minutes. When we came out, a man walked past us just covered in blood.”
Sophie Tedd, 25, had traveled from Darlington to attend the concert with her friend, Jessica Holmes. At the end of the concert, they heard a loud bang and initially wondered whether “a speaker had blown.”
“Then everyone started crying and screaming,” she said. “Everyone ran out. People were pushing each other out of the way. It took a couple of minutes to get out. The police were outside telling us to keep running, to run away from Victoria station.”
Video from inside the arena showed the surreal scene of people scrambling for the exits amid pink balloons. The balloons were part of the choreographed staging for Ms. Grande’s tour, after a segment with projections and lasers.
— Rory Smith and Ben Sisario
The Terrorism Threat in Britain
The Manchester police are working on the assumption that the deadly explosion at the concert was an act of terrorism. If so, it would be the worst act of terrorism in Britain since the 2005 bombings of London’s buses and subway killed 52 people.
But the British authorities, who have foiled numerous terrorist plots, will hardly be surprised. The threat level set by MI5, the domestic intelligence service, has been set at “severe,” the second-highest level, for months, meaning that an attack was considered “highly likely.” And counterterrorism officials have been warning that as the Islamic State comes under more military pressure in Iraq and Syria, it will try to strike abroad.
— Steven Erlanger