A concert with Ariana Grande would have had a robust demographic of “tweens” – children not yet into their teenage years.
We don’t know yet who mounted the attack. But if the pattern holds, it will be a Muslim male.
No confirmation yet regarding this is a terror attack. But noting an individual bleeding from both ankles, two images with knee injuries, and a witness report of “nuts and bolts flying through the air” this seems to be a Tsarnaev-style attack on children.