>> An explosion rocking the St. Petersburg metro system. At least 9 people were killed and 50 injured when the blast tore through a train carriage in the Russian city. Russian president Vladimir Putin was himself in the city at the time, meeting the leader of Belarus. He says he's considering all possible causes for the explosion, including terrorism.
> Law enforcement bodies and special services are working and will do all they can in order to find out the cause of what's happened and to give a full assessment of what's happened. And the city and Federal authorities will do everything necessary to support families of those who've died and support our citizens who were injured.
>> Interfax News Agency quoted an unnamed source saying it was a bomb filled with shrapnel. Emergency services descended on the Sennaya Ploshchad station. Initial reports were of two explosions, however, it was later confirmed the blast occurred in a tunnel between stations.
ssia has been the target of attacks by separatist Islamist Chechen militants in past years.
Islamic State has also threatened attacks in the country in retaliation for Russian military intervention in Syria. The cause of the explosion is still unknown.