At least 37 people were in killed after three explosions went off near a school in west Kabul on Saturday, sources said.
Fifty-six others were wounded in the blasts which happened outside Syed-ul-Shuhada school just as female students were leaving.
Images showed bodies, backpacks and books lying on the ground following the blasts.
There was no immediate claim of responsibility for the attack.
President Ashraf Ghani blamed Taliban for the attack which he termed as a crime against humanity. The group, however, denied involvement and in turn blamed Daesh.
The UN mission expressed its “deep revulsion” and the EU mission in Afghanistan condemned the school bomb as “a despicable act of terrorism”.
“Targeting primarily students in a girls’ school, makes this an attack on the future of Afghanistan. On young people determined to improve their country,” the EU said in a statement on Twitter.