The explosion happened as the train was travelling between the stations Tekhnologichesky Institut and Sennaya Ploshchad of the St. Petersburg Metro, the NAC confirmed.
Terrorism probe has been launched over the blast by Russia’s Investigative Committee.
Health Minister Veronika Skvortsova earlier said that among the victims was a 15-year-old girl, who has burns and a head injury.
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According to health officials, the victims being treated in hospitals vary in age from teenagers to as old as 70. They are suffering from burns, blunt head traumas, shrapnel injuries and lung damage.
“He acted right in the circumstances. The explosion happened in the tunnel between stations, but the driver took the right decision and brought it to the next station, which allowed evacuation and help to the injured to start at once. This may have prevented casualties,” the committee said.
All Metro stations are closed to passengers. Commuters were evacuated from the subway within about an hour of the first reports of the blast coming in.
An undetonated improvised explosive device (IED) was discovered by investigators at the Ploshchad Vosstaniya Station and defused by specialists, the NAC reported. It rejected media reports which claimed that more than one explosion occurred, saying no evidence supporting this was found.
Alleged photos of the IED surfaced on social media. They show a medium-sized leather bag, which apparently held a container filled with explosives, with ball bearings wrapped around it.
Facebook has activated its Safety Check feature for users in St Petersburg. It allows people to let friends and family know that they are OK during a disaster or dangerous situation.
The St. Petersburg city authorities declared three days of mourning for the victims of the Metro explosion.
A St. Petersburg resident told RT that he “was going to Mayakovskaya station [not far from Sennaya Square, the station that was hit] when the alarm went on and the security guards started to block all the entrances. They just told people to get away from the area and suggested not using the Metro today.”
According to the resident, who identified himself as Alex, “there was a bit of panic in the eyes of the people,” both passengers and subway staff alike.
“As there was an announcement that all the stations will be closed due to technical reasons,” people understood that something was wrong and rushed to the exits, he said.
Alex also recalled that he saw ambulances and police cars arriving at the station.