MOSCOW - Russian police killed three militants, including a woman, in a security sweep in the North Caucasus republic of Dagestan Sunday, a police source said.

The operation was launched early on Sunday when a group of militants were blocked in a house in the town of Dagestaniskiye Ogni, some 120 km south of the regional capital Makhachkala, RIA Novosti news agency reported.

The source said the killed woman was the common-law wife of one of the killed men. Another woman was detained.

In another special operation on Thursday, police killed three militants and detained one.

Violence is common in the North Caucasus republics of Chechnya, Dagestan and Ingushetia with militants frequently mounting attacks targeting police officers and authorities.