On Tuesday morning, Chief Constable Ian Hopkins of the Greater Manchester Police said that the deadly explosion at the end of Monday night's Ariana Grande concert in the English city's Manchester Arena was likely caused by one man who exploded an "improvised explosive device" and died in the blast. He also raised the death toll to 22 people, including children, and said 59 people were wounded. British authorities are treating the explosion as a terrorist attack, and Hopkins said police believe the man acted alone but have 400 officers deployed in the investigation, which will try to determine if the attacker was part of a broader network and if nuts and bolts were used as shrapnel, as some concertgoers have reported.
Security was tight at the arena, as for all concerts, and it isn't clear that the suicide bomber was inside the venue at all. Some reports suggest the explosion came from the ticket area, the foyer, or the covered area connecting the arena to the adjacent train station.