A gunman shot and killed a police officer and took more than 20 students hostage at a high school on the outskirts of Moscow on Monday, Russian news website Lifenews reported.
A police spokeswoman said a man entered the school with a rifle and shot a security guard. She said she had no further details and could not confirm any deaths, Reuters reported.
An eyewitness told Rossiya-24 television news that a police helicopter hovered overhead.