"After the interrogation of the accused, the witnesses, the victims and following the results of other inquiry procedures it has been established that the attacker acted with the complicity of his classmates," Petrenko said.
"They have already been indicted and the prosecution requests the court to choose detention as a preventive measure for the designated individuals," Petrenko said.
Investigators said earlier that they suspected that a student had attacked seventh-graders with an axe at a school in Ulan-Ude outskirts. He then threw a Molotov cocktail into a classroom and started a fire, injuring five. The flames had been put out and more than 500 people had been evacuated.