What was it about an arena full of teen and preteen children and their parents, listening to an American pop singer, that so offended the man who detonated the bomb in Manchester last night? We don’t know for sure, although recent tragedies in Berlin, Nice, Paris, and London may give us strong suspicions. The bomber—whose identity is unknown, for now—is dead, along with twenty-two of his victims. Fifty-nine more are hurt, some with life-threatening injuries. The attacker triggered his bomb at around 10:35 p.m. last night, at the end of an Ariana Grande concert, in the foyer of the Manchester Arena, just as fans were coming out of the gig. The timing appeared to have been calculated to inflict as much death and panic as possible. In concertgoers’ videos, the terror in the arena is palpable. A girl recording one video asked the same question, over and over: “What is going on? What is going on?”