At least nine people have died following an explosion on the St. Petersburg metro.
Russia’s Prosecutor General has officially declared the explosion to be an act of terrorism.
Russian officials confirmed that one explosion had taken place at the city's Tekhnologicheskiy Institut metro station at approximately 2:30 P.M. local time.
Initial reports suggested that a second device had exploded on a metro car at the Sennaya Ploshchad station. Police later clarified that only smoke had been seen in the area.
A third, unexploded device was reportedly also found at the city's Ploshchad Vosstaniya station.
Russian news site Gazeta.ru spoke to one eyewitness who was travelling in an adjoining metro car.
“We were in the neighboring train car. The train car was crowded: people were sitting and standing,” she said. “The explosion happened on the track between two metro stations. There was a thundering clap, then a strong smell, smoke. We went to the other end of the train car. People became jammed together. Two women passed out.
"All of this happened while the train car was in motion, the train didn’t stop. Everyone left the train at Technologichesky Institut station. There, we saw that the neighboring train car was shattered, the windows broken, there was no light and blood everywhere.”
The St. Petersburg metro has now been closed, while the Moscow metro is still operating with extra security measures in place, officials announced on Twitter.