Investigators say that a train crash that occurred in northwest Russia late on Friday night, killing at least 26 people, was caused by ‘an explosive device equivalent to 7 kg of TNT’, in what reporters are describing as the worst terrorist attack outside the Caucasus in five years.   A second bomb apparently detonated when officials were at the crash site, but no one was injured.  Aboard the packed, luxury train, seemingly popular with business people and tourists, were two senior officials, both of whom were killed.  According to the Guardian, investigators are focusing on a ‘Chechen link’, in the form of Pavel Kosolapov, whom prosecutors accused of a similar attack in August 2007, on the same train line.  A description of a suspect seen near the scene has reportedly been released.  Survivors have told Ria-Novosti that a lack of first aid kits on board made tending to the injured almost impossible.