At least four students died after a mortar shell hit their school in Andar, some 31km (19mi) south of Ghazni, on Saturday.
Seventeen others, including two teachers, were reportedly injured in the strike, the source of which is yet to be ascertained.
The shell hit the Mullah Noh Baba school during working hours while fighting was ongoing between government forces and Taliban fighters, according to locals, who say they are not aware of which side fired the deadly mortar.