Several regions in Russia's restive North Caucasus on Thursday tightened security measures, following the discovery of six dead bodies with gunshot wounds in the Stavropol territory. The Kabardino-Balkaria republic's government said in a statement that the murderers may come from that region, and that it was helping investigate the criminal case. "Simultaneously, security measures are being tightened in the republic," said the statement. On Wednesday, authorities found six bodies "without signs of life left in cars" in two villages in Stavropol, some 1,400 km south of Moscow. Besides, an improvised bomb went off near one of the cars, injuring nobody, while another bomb disposed safely. Russian Investigative Committee spokesman Vladimir Markin has said the six murders were interconnected. The North Caucasus has been on high alert after two separate suicide bombings hit Volgograd, some 690 km northeast of Sochi, where the 22nd Winter Olympic Games were slated for next month, leaving at least 34 people killed and over 100 more injured. Moscow has deployed tens of thousands of forces to safeguard the Games, the first to be held in the country.