Ten people were killed and more than 20 others were injured after a blast ripped through an underground metro station in St Petersburg, Russia, on Monday. Victims said there were children among the injured, according to news channel Russia Today. Russian Prime Minister Dmitry Medvedev has referred to it as a terrorist attack, reported BBC.

The explosion took place while the train was travelling between Sennaya Ploshchad metro station Tekhnologichesky Institut station in the heart of the city around 2.30 pm (local time), the National Anti-Terrorism Committee said. “All the victims are receiving the necessary medical and psychological assistance,” the NAC said.

Earlier reports claimed that there were two explosions, but the NAC said there was no evidence to prove this. Another explosive was found and diffused at the nearby Ploshchad Vosstaniya station, according to Russia Today. All metro services have been shut down. Sennaya is one of the most central metro stations in St Petersburg.

The bombs were reportedly low-intensity, homemade ones. Helicopters were used to evacuate citizens from the scene. At least 25 victims have been hospitalised, including a child.

Bomb squads and ambulances have been sent to the spot. People shared images from the blast site on social media, which showed a door of one of the train carriages blown apart.

Kremlin spokesperson Dmitry Peskov told Russian news agencies that President Vladimir Putin had been informed about the explosion. Putin expressed his condolences and said all possible motives for the attack will be investigated, including terrorism.

In a Facebook post, Prime Minister Dmitry Medvedev wrote, “All those who were injured in the terrorist attack in St Petersburg metro will receive all the medical help they need... My most heartfelt commiserations go out to the friends and relatives of the victims of the explosion. This is our common pain.”