Sheera Frenkel BuzzFeed News Foreign Correspondent

The attack on a school in the Pakistani city of Peshawar might be the worst in the country’s history, but human rights groups say it is part of an ongoing trend that has seen more than 1,000 schools targeted since 2009.

“This is a particularly horrific case, in which more than 130 school children lost their lives, but it happens in a smaller scale all too often,” said Diya Nijhowne, director of the Global Coalition to Protect Education from Attack.

At least 130 people were killed on Tuesday, including more than 100 under the age of 16, as they studied in the army public school in Peshawar. The Pakistani Taliban (TKK) took credit for the attack, saying six gunman scaled the walls of the school just after 10 a.m. local time.

Taliban spokesman Muhammad Khorasani told AFP there were six attackers.

“We are doing this because we want them to feel the pain of how terrible it is when your loved ones are killed,” said Khorasani.

He claimed that the gunmen sent to storm the school were under orders to “shoot the older students but not the children.”

International aid groups, including Human Rights Watch and the International Crisis Group (ICG), report that at least 1,000 schools have been attacked by the Taliban in Pakistan since 2009, though they note the number could be much higher.

“Any schools, but particularly girls’ schools, are considered soft targets to further the militants’ ultra-orthodox agenda,” the ICG said in a report earlier this year. “The schools have become a target because they, “promote Western decadence and un-Islamic teachings.”

Malala Yousafzai, the Nobel Prize-winner who has continued to campaign for girls education despite after being shot in the head by the Taliban, is perhaps the most famous case of a school attack in Pakistan. When the Taliban gained control in 2007 of the Swat Valley where Yousafzai lived, it banned girls’ education past the fourth grade. Between 2007 and the attack on Yousafzai in October 2012, 119 girls schools in the Swat Valley were attacked.

Nijhowne said that the schools are often state-run, which makes them an easier target for Taliban militants looking to destabilize the government.

“Schools are often seen as an instrument of the state,” she said. “They are government-run schools so the teachers within them are seen as government employees. It’s an easy way to attack the state rather than a military installation.”