russian train crash... terrorism?

an article in the new york times describes a crash involving a 20 car luxury train on its way from Moscow to st. Petersburg. apparently the crash was begun by a bomb, 15lbs. of TNT, that had been laid on the tracks and exploded once half of the cars had passed. a five foot crater, multiple fatalities and even more injury's are all that is left on the scene now. the article says the crash happened in a very inopportune location for emergency personnel to reach quickly, apparently all the roads to that part of the tracks are unpaved and full of ditches. the train itself is known as a means of travel for the "higher society" in Russia, a few public officials were among the fatalities.

To me, this doesn't seem to be in question... it was a terrorist attack, parts of the homemade bomb were found, along with the crater and given that the location was so remote, and the train was a viable means of transportation for important government officials i couldn't see how anyone would argue otherwise. the article goes on to explain Russia's more recent history with terrorist attacks, mentioning multiple times the Chechnya's and their past terrorist activity against Russia. personally, i don't believe that there will be much in the way of investigation, at least i doubt we will find out who planted it unless some group claims responsibility. but once again, a needless attack has taken innocent lives in the name of some movement that probably has very little to do with anyone on board that train.