LONDON — Some of the girls had barely reached puberty. Many had come with parents in tow. At least one was only 8 years old.

It is not clear whether the bomber who killed 22 Ariana Grande fans, wounded 59 and incited a mass panic at her concert in the Manchester Arena on Monday night had intended for his homemade device to explode among victims who were young and included many girls.

But the traumatizing effects put the attack in the same category as the Beslan school siege in Russia, the Peshawar school massacre in Pakistan and the mass kidnapping of schoolgirls in Chibok, Nigeria: It grabbed the adult world’s attention in ways that some indiscriminate attacks do not.

“It’s intended to shock,” said William McCants, a senior fellow at the Center for Middle East Policy at the Brookings Institution and an authority on the Islamic State, which claimed responsibility for the Manchester assault. “You get maximum fear by attacking a vulnerable population: kids.”

Mr. McCants, the author of the 2015 book “The ISIS Apocalypse: The History, Strategy and Doomsday Vision of the Islamic State,” said that “the thing with ISIS is, it doesn’t worry about offending mass public opinion.”

By Tuesday evening, the police in Manchester had publicly identified only a few of the dead. The details that were emerging about the victims reinforced what Mr. McCants and others described as the shock value craved by plotters of such attacks.