At least 10 people have been killed, and more than 50 wounded, following explosions on two train carriages at metro stations in the Russian city of St. Petersburg.
At least 10 people were killed in explosions in two train carriages at metro stations in St. Petersburg on Monday, Russian authorities said.
Russian President Vladimir Putin, who is in St. Petersburg for a meeting with Belarussian leader Alexander Lukashenko, said the cause of the blasts was not clear and efforts were underway to find out. He said he was considering all possibilities including terrorism.
Spokesperson Dmitry Peskov confirmed that President Putin had been in St. Petersburg earlier on Monday but now outside the city.
The Interfax and RIA news agencies reported that at least 50 people had been injured. Interfax said one of the blasts may have involved a device filled with shrapnel.
Video showed injured people lying bleeding on a platform, some being treated by emergency services. Others ran away from the platform amid clouds of smoke.
Russia has been the target of attacks by Chechen militants in past years. Chechen rebel leaders have frequently threatened further attacks.
At least 38 people were killed in 2010 when two female suicide bombers detonated bombs on packed Moscow metro trains.