An explosion in St Petersburg metro tunnel: Still early to tell cause of incident

At least eleven people are dead and dozens injured in Russia after an explosion tore through a train carriage in a St Petersburg metro tunnel, with authorities calling it a probable terrorist attack, it coincided with a visit to the city by President Vladimir Putin.

Russian President Vladimir Putin, left, lays flowers at a place near the Tekhnologichesky Institut subway station in St.Petersburg, Russia Source: AP