Russia mourns victims of deadly concert hall attack

Russia lowered flags to half-mast on Sunday for a day of mourning after scores of people were gunned down with automatic weapons at a rock concert outside Moscow in the deadliest attack inside Russia for two decades. President Vladimir Putin declared a national day of mourning after pledging to track down and punish all those behind the attack, which left 133 people dead, including three children, and more than 150 were injured. "I express my deep, sincere condolences to all those who lost their loved ones," Putin said in an address to the nation on Saturday, his first public comments on the attack.