It was gathered that “Eight schoolchildren and a teacher were killed,” a source told the Interfax news agency.
Ten more people were injured, said state news agency TASS.
Spokespersons for police and the emergencies ministry refused to comment.
News agencies reported that two unidentified people had carried out the shooting and one, a 17-year-old, had been detained.
Images broadcast on state television from the scene showed dozens of people outside the school building with fire services and police vehicles lining nearby streets.
A source told the Interfax news agency that a second shooter had barred himself in on the fourth floor of the building.