Gunmen kill four policemen in Russia's Dagestan MAKHACHKALA, Russia (Reuters) - Four policemen were killed in Russia's violence-plagued Dagestan region on Sunday when unidentified gunmen opened fire on their car, local investigators said. The police officers were on their way back from a village of Burshi, some 100 km (62 miles) south-west of regional capital Makhachkala, when their car was attacked by two assailants. Insurgents are fighting to carve out an Islamic state in Dagestan - an ethnically mixed, mostly Muslim region in the North Caucasus between Chechnya and the Caspian Sea. Dagestan drew an international spotlight following an April bomb attack at the Boston Marathon in the United States. One of the bombing suspects, Tamerlan Tsarnaev, went to Dagestan during a six-month visit to Russia last year, and Russian and U.S. authorities are trying to determine whether he had contacts with militants there. Russian President Vladimir Putin has deployed extra security to try to prevent any attacks on the 2014 Winter Olympics next February in the Black Sea resort city of Sochi, separated from the most violent North Caucasus regions by a mountain range. Writing by Alexei Anishchuk; Editing by Louise Ireland