The statement said that Arakan Army members attacked a group of Myanmar military personnel during their security operation in Buthidaung township on Thursday morning.
The security forces returned fire, forcing Arakan Army members to retreat.
During their retreat, they launched mortar fires at 1.2km from Khami Chaung village.
One mortar hit the school in the village, injuring students who were playing in front of the school, the release said.
Five of the injured were sent to Buthidaung township hospital while the rest were treated at a clinic of a military base camp.
The Arakan Army, a Rakhine rebel group fighting for the rights of ethnic Rakhine people in Myanmar, clashes with the Myanmar military regularly and has been designated as a terrorist group by the government. - Xinhua/Asian News Network