MOSCOW — A teenager stormed his school in Moscow on Monday, shooting dead a teacher and a police officer and taking 20 of his classmates hostage, officials said. Within two hours, Russian police and soldiers had entered the school and disarmed and arrested the shooter.

The Interfax news agency said the boy’s father helped with negotiations.

The attacker arrived at the School 263 in the outskirts of the Russian capital at noon (3 a.m. ET) armed with two rifles, Interior Ministry spokesman Andrei Pilipchuk told NBC News. The spokesman added that he forced a security guard at gunpoint to take him to the biology classroom.

He then allegedly shot dead the school’s geography teacher and took the 20 10th-graders hostage.

Asked if the pupil had a previous disagreement with the teacher, Pilipchuk said: “The conflict with the teacher is one of the versions the investigators are working on.”

The teenager killed one police officer and wounded another who arrived at the scene in response to an alarm activated by the security guard, Pilipchuk said.

“The door to the classroom was half-open, so when the policemen arrived to the school the student started shooting at them,” he told NBC News.

Footage broadcast on the Russia24 television station showed pupils running from the building while a police helicopter landed on a snow-covered area outside.

The incident comes just days before the opening of the Sochi Winter Olympics on Friday. The run-up has been dominated by concerns about terrorism and security after deadly bombings in the city of Volgograd in December and threats by militant groups.