At least 19 people were killed and dozens more injured in a suicide bombing at a tutoring center in Kabul on Friday, local authorities said. While there was no immediate claim of responsibility for the attack, the blast took place in the western area of the Afghan capital populated by Hazara—an ethnic minority who have previously been attacked by radical groups including ISIS. Some 27 people survived the bombing but were wounded, Kabul police spokesperson Khalid Zadran said. While schools are usually closed on Friday in Afghanistan, the tutoring center was holding an exam at the time of the attack, Zadran added. “Attacking civilian targets proves the enemy's inhuman cruelty and lack of moral standards,” he said. A source at a local hospital said 23 had been killed in the attack, while a Taliban source claimed 33 were dead, including female students. “UNICEF is appalled by the horrific attack,” the humanitarian organization tweeted Friday. “Violence in or around education establishments is never acceptable. Such places must be havens of peace where children can learn, be with friends, and feel safe as they build skills for their futures. Children and adolescents are not, and must never be, the target of violence.”