Three others who were injured were taken to a military hospital, the ministry's news service reported.
The accident occurred at a firing range near the town of Mulino in the Nizhny Novogorod region, ITAR-Tass said Wednesday.
A spokesman for the Main Military Prosecutor's Office said investigators were at the scene to determine the cause of the blast, and the Defense Ministry said a commission led by Col. Gen. Arkady Bakhin, commander of the Western Military District, headed immediately for the site.
RIA Novosti reported a regional law enforcement source said the blast was tentatively blamed on safety violations while moving the ammunition.
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