Police in Russia investigating last week’s bombing of a Moscow to St Petersburg train have reportedly identified two possible suspects.Some 26 people died in Friday’s attack and dozens more were injured. Little is being released about the suspects, but authorities are focusing on a house possibly linked to the case. Police have also released a composite sketch of one of the suspects. Amid increasing concerns about security, authorities are calling for vigilance. Security has been stepped up at train stations and many entertainment events have been postponed or cancelled. One Russian newspaper reports that authorities suspect the bombing may be the work of a known criminal gang, already linked to a similar attack on the same track in 2007.