St Petersburg metro blast: What we know so far

• Video report by ITV News Security Editor Rohit Kachroo

A blast has ripped through an underground train in Russia's second-largest city, killing at least 14 people and injuring dozens more.

Here's everything we know so far:

• At approximately 14:40 local time on Monday (11:20 GMT), an explosion ripped through an underground train in St Petersburg, Russia.

• The explosion occurred as the train was travelling between Sennaya Ploshchad and Tekhnologichesky Institut stations.

• Instead of stopping in between stations after the blast, the driver chose to continue to Tekhnologichesky Instituta.

• Russia's Investigative Committee praised the diver for aiding evacuation efforts and reducing the danger of surviving passengers.

• The entire St Petersburg underground system - which serves two million people a day - was shut down and evacuated.

• Hours later, Russia's Anti-Terrorism Committee said they found and deactivated a bomb, rigged with shrapnel disguised as a fire extinguisher, at another station - Vosstaniya Square station.

• Authorities in Russia identified a 23-year-old man from Central Asia for being responsible for the blast.

• Intelligence officials in Kyrgyzstan have since identified the suspect as a Kyrgyz-born Russian citizen.

• They said the suspect was a suicide bomber and carried an explosive device onto the train in a rucksack. He is believed to have links with radical Islamists.

• Police believe the same man, not a second suspect, planted the bomb at Vosstaniya Square station.

• President Putin says all causes are being considered, including terrorism - however Russia Prime Minister Dmitry Medvedev has described the blast as a "terrorist attack".