A major intelligence investigation is underway in Russia after Friday night’s passenger train crash.Confirmation that three carriages of the Moscow to St Petersburg express were blown off the tracks by a bomb has turned the site into a crime scene. At least 26 people died and up to 100 were injured in the incident, which is the worst Russian bomb attack outside the North Caucasus in recent years. At an emergency meeting, Russian President Dmitry Medvedev sent his condolences to the families of the dead and held a minute silence. There are fears of a terrorist upsurge in Russia’s heartland as speculation grows over who planted the bomb. So far no group has come forward. Alexander Bortnikov, head of FSB’s domestic intelligence service told reporters: “At present there are a few scenarios of what happened, they are being investigated. A criminal investigation has been started under the terrorist act along with a case of unlawful use of weapons.” Analysts specialising in political terrorism believe a recent escalation in violence in Ingushetia and Chechnya could point to the culprits. Military analyst Pavel Felgenhauer said: “There’s no kind of organised group. There are networks of nationalists and there are networks of Islamists and they are kind of semi-independent networks. They don’t have a head you can chop off or with whom you can talk.” Security at Moscow’s mainline stations and elsewhere has been stepped up. The fact that a second bomb was found and detonated without injury near the first has unnerved many commuters.