Update 16:11
Russia's health minister has confirmed that 10 people have been killed - and at least 50 injured.
Update 16:09
Russian anti-terror officials are now reporting that at least 9 people have been killed and at least 50 injured, in an explosion in the Metro system in the city of St Petersburg.
A second device was also found and has been made safe.
It is now being reported that the explosion happened between two stations.
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Update 14:05
At least 50 people are injured from the blast.
There's speculation that there may have been more than one explosion.
The country's president Vladimir Putin has been informed.
He says that they are still trying to establish the cause - and isn't ruling out terrorism.
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At least 10 people have been killed in a metro explosion in Russia.
The blast happened in an underground train station in the city of St Petersburg.
It's been reported that all metro stations in the area have been shut as a result of this.
More to follow.
