By Ben Aris in Berlin A group of gunmen attacked a crowd of concert goers at the Crocus City Hall in western Moscow on the night of March 22, killing at least 40 and injuring up to a 100 more, according to the Federal Security Service (FSB). There is no information on who the gunmen were. Video from those in the building show horrific scenes of half a dozen men walking through the building shooting civilians with Kalashnikov machine guns at point blank range. They were wearing military fatigues and assault vests with spare ammo and appear to be military trained. Other videos show the entrance …