ON-DON, Russia, March 14 , SPA -- Three servicemen were killed Friday in the latest clashes in Russia's volatile North Caucasus provinces, local law enforcement authorities said, according to AP. In the worst violence, two interior troops were killed during a security sweep in the province of Dagestan east of Chechnya, an Interior Ministry spokesman said. Security forces killed six suspected militants in the raid on a camp in the Buinaksk region allegedly serving as a base for planned terrorist attacks. Authorities said a large cache of weapons was found on the site. Dagestan suffers from violence linked to criminal activities and insurgent activity that has spread from Chechnya. Bombings against police convoys and other representatives of federal authority, once common, have diminished in recent years. But the last few weeks have seen a spike in attempted attacks against police in the republic. In a separate incident, unidentified assailants shot and killed an officer of the Federal Security Service in the province of Ingushetia that borders Chechnya to the west, according to a statement from the regional branch of the federal Investigative Committee. Another two FSB officers were wounded in the attack.