Moscow – A terrorist blast shook on Monday the Russian city of St. Petersburg when it ripped through a train carriage at St. Petersburg Metro tunnel, killing 14 people and injuring at least 47.

The blast, which happened at 2:40 pm, coincided with the visit of President Vladimir Putin to the city.

Russia’s Investigative Committee and the General Prosecutor’s office have deemed the explosion as a “terrorist act,” but said they were also considering several scenarios.

Official representative of the Prosecutor’s office Alexander Kurennoy told the TV channel Rossiya-24 the bombing was terrorist attack and that the examination of the explosion would be comprehensive.

Monday’s blast is the first to hit Russia in over two years.

The Investigative Committee said the blast occurred when the metro train was crossing between the Sennaya Ploshchad station and Tekhnologichesky Institut on one of the city’s north-south lines.

Russian media outlets reported that the explosive was placed in a briefcase left on the train. Security sources said the power of the homemade explosive device contained around 200 to 300 grams of TNT.

Investigative Committee spokeswoman Svetlana Petrenko told TASS news agency on Monday: “The explosion occurred between two stations. The driver made the right decision not to stop the train, but take it to the next station, which allowed for promptly starting the evacuation and providing assistance to the injured. This helped prevent a heavier death toll.”

Hours after the first blast, security officials said they found another explosive device at the Ploshchad Vosstania metro station in St. Petersburg, hidden under a fire extinguisher, but it was defused.

The city of St. Petersburg announced three days of mourning beginning Tuesday.

The Investigative Committee said all metro stations in St. Petersburg have been closed after being fully evacuated.