Russian President Vladimir Putin has declared Sunday a day of national mourning for the 137 victims of the recent attack on a Moscow concert hall. The attack, which occurred on Friday, is the deadliest in Russia in two decades.
President Putin has vowed to punish the perpetrators of the attack and expressed his condolences to those who lost loved ones. In a statement, he said, 'The whole country, our whole people, mourns with you.'
