Updated

Moscow police say a student burst into a high school Monday with a rifle and fatally shot a police officer and a teacher before briefly taking a class full of children hostage.

Investigators told the Associated Press that the student had been taken into custody alive. Details of the student's identity were not immediately available.

Russia Today reported that the gunman entered School No. 263 and threatened the school's security guard before making his way to a biology classroom, where he took 29 10th-grade students hostage before releasing most of them soon after. It is not clear when the rest of the children were released.

The security guard was able to call police to the scene with an alarm button, and the gunman reportedly shot two of the responding officers, one fatally. It is not clear when he shot the teacher.

The school was evacuated of the rest of the students, and police spokeswoman Karina Sabitova told the Associated Press that no children were injured.

All Russian schools are required to have at least one armed security guard as the result of legislation passed in the wake of the 2004 Beslan school hostage crisis, which ended in the deaths of over 300 people, including nearly 200 children.

The Associated Press contributed to this report. 

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