An army unit that pelted a Dagestani school with mortar rounds was aiming for insurgents hiding elsewhere in the area, the Investigative Committee said on Friday.
Several rounds exploded at the premises of a boarding school in the city of Buinaksk on early Thursday, injuring no one, but damaging the building.
The incident was initially blamed on military exercises, but the Defense Ministry later said none were being held in the district at the time.
An investigation showed that the army was hunting Islamist rebels around Buinaksk on Thursday night, the committee said.
But the squad commander gave the wrong directions to the mortar crew, which fired at the school instead of a militant hideout, the report said.
No militants were reported killed in the vicinity of Buinaksk on Thursday, though the leader of the so-called “Kizlyar gang” was shot dead some 160 kilometers to the north of the city.