1027 GMT February 18, 2020
The soldier – who has been detained – might have been suffering from mental health problems, they said, according to BBC.
The shooting happened in the village of Gorny, not far from the city of Chita, on Friday evening.
The soldier – whose name has not been released – was guarding the base at the time. He is believed to be a conscript.
The shooting happened at 18:20 local time (1120 GMT) during a change of guard at the base in the Transbaikal region, the Russian Ministry of Defense said.
Russian media reported that two officers and six conscripts were killed.
Military service is mandatory in Russia for all male citizens aged 18-27. They typically serve 12 months, and can then sign a professional contract to continue in the armed forces.