A police spokeswoman says none of the children who were in School No. 263 were hurt.
She says the student also wounded a second police officer who had responded to an alarm from the school.
A spokesman for Russia's main investigative agency says the student showed up at the school with a gun and a school security guard tried to stop him. The guard was able to hit an alarm button before following the student to a 10th-grade biology class.
A spokesman for the Investigative Committee says the student fatally shot a teacher and opened fire on police officers who responded to the alarm.