Police have killed three suspected militants, including a woman, in a security sweep in the Republic of Dagestan in Russia\'s volatile North Caucasus region, a police source said on Sunday. Police launched a special operation early on Sunday after blocking a group of militants in a house in the town of Dagestaniskiye Ogni, some 120 km (75 miles) south of the capital Makhachkala. A counter-terrorist regime was imposed to battle the gunmen. \"According to preliminary information, police killed two militants and a woman, the common-law wife of one of those killed. Another woman was detained,\" the police source said. More that a decade after the end of a federal war against separatists in Russia\'s North Caucasus republic of Chechnya, Russian security forces continue to fight militants in other regions in the area, who stage frequent attacks on security forces, police and civilians.