MOSCOW, April 3. /TASS/. Russia’s Investigative Committee has qualified the explosion on a St. Petersburg metro train as a terrorist attack. At the same time, the investigators are not excluding other versions, apat from terrorism, the IC spokeswoman Svetlana Petrenko has told TASS.

"The criminal case was opened under Article 205 of the Criminal Code [Act of Terrorism], but the investigators are going to proceed along other lines of inquiry, too," she said. 

The investigators were now looking into all circumstances of the explosion. IC chief Aleksandr Bastrykin has commissioned the IC’s special investigations department to probe into the affair.

"According to preliminary findings, a yet-to-be specified explosive device went off on a train between the Tekhnologichesky Institut and Sennaya Ploshchad stations at 14:40 Moscow time. There were casualties. A team of experienced investigators and forensic specialists from the IC’s head office has been dispatched to St. Petersburg," Petrenko said.

The specialists are going ahead with crime scene investigation. All pieces of important material evidence are being collected, witnesses and metro employees questioned and the number of casualties is being specified.

Preliminary findings indicate that the train driver’s actions were correct.

"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," Petrenko said.

The administration of St. Petersburg has declared a three days mourning starting Tuesday, the governor’s spokesman Andrey Kibitov wrote on Twitter.

In light of the St. Petersburg metro blast, transport security measures have been tightened in Moscow as well. Moscow mayor Sergei Sobyanin conveyed his condolences to the families and friends of those killed.