A suicide bomber at the Kaaj Higher Educational Center in Kabul, the capital of Afghanistan, exploded a bomb in a classroom on Friday, killing no less than 19 students.

They were taking a mock university exam at the school in the Dasht-e-Barchi area when they were attacked, according to the police and witnesses, as reported by BBC.

While no terrorist group has claimed responsibility for the attack, it was reported that many of the areas are minority Hazaras, who have been targeted by Islamic State (IS) militants and the Taliban.

The third-largest ethnic group in Afghanistan is the Shia Muslim Hazaras.

“Students were getting ready for an exam when a suicide bomber targeted this learning center. Sadly, 19 people have died, and 27 more have been injured,” according to Kabul police spokesman Khalid Zadran.

A student of the school, Akbar said most of the victims were girls. “We were around 600 in the classroom. But most of the casualties are among the girls,” Akbar said.

Families and friends have flooded to hospitals to check for loved ones who were hurt in the attacks.