Four years ago, Chechen terrorists took over 1,000 adults and children hostage at the school in Beslan, North Ossetia. In the course of 'liberating' them, some 330 were killed and more than 800 wounded.
To date, one terrorist has been punished, but there has been no official investigation of the role of the Russian security services, despite protests from witnesses who believe that Russian officials opened fire and caused the deaths of the hostages. For example, some witnesses charge that the first casualties were caused by flamethrowers, fired by Russian special forces into the building where the hostages were being held. Instead, then President Putin used the tragedy to introduce 'reforms' whose purpose was to tighten the Kremlin's control. See details here, thanks to Radio Free Europe.