By Jason Hanna

CNN

(CNN) -- At any Ariana Grande concert, teenage and preteen girls make up a good deal of the crowd.

That was the case Monday night, when a bomb exploded just outside Manchester Arena as people were leaving a show by the 23-year-old US pop star and former kids' TV actor. Concertgoers ran down stairs to escape the 21,000-seat arena as frightened children and teenagers screamed.

At least 22 people, including children, were killed in the terror bombing. One of the victims was an 8-year-old girl.

This is one of many times in this century alone that a terror attack targeted children or a place where youths would have been expected to gather. Here are just a few other examples:

Afghanistan: Poison and acid attacks

Numerous schoolgirls have been attacked in Afghanistan over the past two decades, in part to dissuade them and others from attending school.

Hundreds have been hospitalized over the years, for example, because of poisoning attacks at their schools -- including contamination of their drinking water and the suspected spraying of toxic substances.

Acid has been thrown at other schoolgirls, disfiguring them.

Girls were forbidden to go to school when the Taliban ruled the country from 1996 to 2001. The schools resumed regular operations after a US-led invasion toppled the regime, but have still come under attack in the post-Taliban era.

Nigeria: Numerous Boko Haram attacks against students

The radical Islamist group Boko Haram has been blamed for many attacks against students in Nigeria. Among them:

• July 2013: Assaults on student dormitories in a secondary school in Mamudo left 41 students and a teacher dead.

• February 2014: Gunmen killed dozens of students ranging in age from 13 to 17 at the Federal Government College in Buni Yadi, UNICEF says.

• November 2014: At least 58 students were killed and 117 injured when a suicide bomber attacked a crowded student assembly ‎ground inside Government Comprehensive Secondary School in Potiskum.

Boko Haram militants also kidnapped more than 270 girls and women, ages 15 to 18, from a boarding school in Chibok, sparking global outrage. Scores of the captives either escaped or were released over the past few years; 113 remain unaccounted for.

Norway, 2011: Massacre at a political youth camp

Anders Behring Breivik, an ultranationalist who authorities say was upset about the rise of multiculturalism in Norway, detonated a bomb in Oslo, killing eight, before shooting to death 69 people -- including minors -- at a Labor Party youth camp on Utoya island.

After being charged with committing acts of terror and voluntary homicide, he was judged sane and sentenced to 21 years in prison.

Pakistan, 2012: Malala Yousafzai shot

Teen activist Malala Yousafzai was shot in the head by Taliban gunmen as the 14-year-old headed home from school in Pakistan's conservative Swat Valley in October 2012.

Malala had enraged the militant group by blogging against extremists who wanted to force girls to stay at home instead of going to school, and had won Pakistan's first National Youth Peace Prize in 2011 for her efforts.

She survived and returned to school months after the attack, and won the Nobel Peace Prize in 2014.

Pakistan, 2014: Attackers kill 132 children at school

Taliban militants raided an army-operated school in Peshawar in December 2014, killing at least 145, including 132 children.

Most of those killed were between the ages of 12 and 16. Some of the victims were shot in an auditorium where they'd been taking exams.

More than 100 people were injured, many of them suffering gunshot wounds.

A Pakistan Taliban spokesman told CNN that the attack was revenge for the deaths of hundreds of tribesmen during army operations.

Russia, 2004: Beslan school siege

Heavily armed Chechen separatists took more than 1,000 people hostage for days in a school gymnasium in Beslan, North Ossetia. After Russian troops moved in to end the standoff, more than 330 people -- including more than 180 children -- were dead.

In 2006, the only surviving hostage-taker was sentenced to life in prison.