A blast caused by an unidentified explosive device wounded three at a military academy in Russia’s northwestern city of Saint Petersburg, Russian news agencies reported the defense ministry as saying.
“At about 1:30 p.m. [10:30 GMT], in St. Petersburg, an unidentified unshelled object exploded in one of the offices of the administrative building of the Mozhaysky Military and Space Academy,” Sputnik reported the Russian Ministry of Defence as saying, adding that three people were being treated for non-life-threatening injuries.
It described the device as lacking casing, meaning that it was not a military device such as a mortar shell.
“Everyone is alive,” Saint Petersburg’s acting governor Alexander Belov told the media.
“Three people are injured, one is lightly injured,” Belov said, without clarifying whether that made the total number of wounded three or four.
The Investigative Committee opened a criminal case into the incident, saying it was working to establish “the origin of the detonated object”.
Police had sealed off the area around the academy, an AFP journalist saw, and cadets and staff were leaving the grounds. Fire engines were also driving out of the gates.
TASS news agency reported that military prosecutors were inspecting the site.
A cadet who gave her name only as Natalya told AFP that “everyone is being evacuated.”
She added that “it looked like something exploded on the first floor” but said she did not have any more information.
An emergency services official told RIA Novosti that the blast reverberated in a first-floor classroom, causing a staircase to collapse and trapping around 20 people.
Local independent news site Fontanka reported that mine clearing specialists were also at the scene.
There was no visible damage to the building.
Earlier, state news agency RIA Novosti reported that four cadets were injured, citing emergency services sources.
The explosion occurred during an attempt to move an undetonated shell, St. Petersburg-based 78.ru news reported.
The blast caused a stairway to collapse, trapping 15 people, the report said.
The A.F. Mozhaysky Military-Space Academy is overseen by the defense ministry and trains officers to serve in air and space defence and other branches of the armed forces.
With reporting from AFP