Unknown gunmen shot dead two police officers in Russia’s volatile North Caucasus republic of Dagestan late on Saturday, the republic’s Interior Ministry said. \"A group of unknown assailants opened fire at two parked police vehicles,\" a spokesman told Russian News Agency (RIA Novosti). \"Two policemen died at the scene from sustained injuries,\" he added. An investigation and search for gunmen is underway, he said. The troubled region sees frequent attacks on police officers and government officials as Moscow continues to battle the insurgency there.