A bomb blast caused the derailment of a Russian express train, killing at least 39 people and injuring more than 90. The Nevsky Express derailed in remote countryside last night as the train travelled between the capital Moscow and St Petersburg. In a statement, the Russia's federal investigative committee said Investigators found elements of an explosive device at the scene. Head of Russia's domestic intelligence service Alexander Bortnikov told President Dmitry Medvedev that a bomb equivalent to seven kilos of TNT had been detonated. News agencies report said Russia's prosecutor-general has opened a criminal case on terrorism charges.There was no immediate confirmed claim of responsibility for the attack. In 2007, a bomb on the same line derailed a train, injuring nearly 30 passengers.