MOSCOW — An armed teenager burst into his Moscow school on Monday and killed a teacher and policeman before being taken into custody, investigators said.

None of the children who were in School No. 263 were hurt, said Karina Sabitova, a police spokeswoman at the scene.

The student also wounded a second police officer who had responded to an alarm from the school, she said.

A spokesman for Russia’s main investigative agency said 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.

The student fatally shot a teacher and opened fire on police officers who responded to the alarm, Vladimir Markin, spokesman for the Investigative Committee, said in a statement.