Four people were injured in a blast at a military academy in Russia's second city of Saint Petersburg, news agencies reported citing emergency services.
"As a result of an explosion, four cadets were injured according to preliminary information," an emergency services official told RIA Novosti state news agency after the blast at the Mozhaisky academy in the city centre.
"What precisely exploded is not yet known," the official said.
The academy is overseen by the defence ministry and trains officers to serve in air and space defence and other branches of the armed forces.
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