TOPSHOT - A picture shows the damaged train carriage at Technological Institute metro station in Saint Petersburg on April 3, 2017. Around 10 people were feared dead and dozens injured Monday after an explosion rocked the metro system in Russia's second city Saint Petersburg, according to authorities, who were not ruling out a terror attack. / AFP PHOTO / STR (Photo credit should read STR/AFP/Getty Images)
ST PETERSBURG, RUSSIA -- APRIL 3, 2017: Locals near Tekhnologichesky Institut station of the St Petersburg metro in the aftermath of a blast that hit a train carriage between Sennaya Ploschad and Tekhnologichesky Institut stations at 14:40 Moscow time; according to Russian National Antiterrorism Committee several people were killed in the explosion. Alexander Demianchuk/TASS (Photo by Alexander Demianchuk\TASS via Getty Images)
ST PETERSBURG, RUSSIA -- APRIL 3, 2017: Police officers near Tekhnologichesky Institut station of the St Petersburg metro in the aftermath of a blast that hit a train carriage between Sennaya Ploschad and Tekhnologichesky Institut stations at 14:40 Moscow time; according to Russian National Antiterrorism Committee several people were killed in the explosion. Alexander Demianchuk/TASS (Photo by Alexander Demianchuk\TASS via Getty Images)
ST PETERSBURG, RUSSIA -- APRIL 3, 2017: A man with bleeding hands at the entrance to Tekhnologichesky Institut station of the St Petersburg metro in the aftermath of an explosion which occurred in a train at 14:40 Moscow time; according to Russian National Antiterrorism Committee several people were killed in the explosion. Anton Vaganov/TASS (Photo by Anton Vaganov\TASS via Getty Images)
ST PETERSBURG, RUSSIA -- APRIL 3, 2017: An emergency service helicopter and a police car near Tekhnologichesky Institut station of the St Petersburg metro in the aftermath of an explosion which occurred in a train at 14:40 Moscow time; according to Russian National Antiterrorism Committee several people were killed in the explosion. Peter Kovalev/TASS (Photo by Peter Kovalev\TASS via Getty Images)
