Security forces killed four people in an area near Chechnya on Saturday, a day after a top intelligence official said violence was spreading throughout the Northern Caucasus region.
Officials in Dagestan, a region east of the troubled Chechnya, said police and other troops had surrounded a house in the dead of night after observation suggested it was a centre for extremist activity.
The occupants refused to surrender and, after children were allowed to leave, a gunbattle erupted, lasting until after dawn. Four men were killed and three women were taken into custody in the regional capital, Makhachkala.
"We cordoned off the area where the persons in question were located and proposed that they surrender and bring the children out," Dagestan's Interior Minister Adilgerei Magomedtagirov, told NTV television. Television footage showed the house badly damaged and in flames. Two women were shown undergoing a search.
On Friday, Nikolai Patrushev, head of the FSB counter-intelligence agency, said separatists waging an insurgency in Chechnya since 1994 intended to hit targets in nearby regions.
"Terrorists have shifted the accent of their activities to the territory of the republics bordering Chechnya," he told a meeting of security officials in southern Russia. Russia has fought two wars against separatists in mainly Muslim Chechnya with heavy loss of life. Despite recurring attacks on its forces there, Moscow says the region is under control and functioning normally under a pro-Moscow government.
Dagestan, a mountainous region on the Caspian Sea and home to a mix of several dozen ethnic groups, has been struck by a variety of violent attacks in recent years. Militants have also hit targets in Ingushetia, a region to the west, whose residents are closely related to Chechens. More than 330 people, half of them children, died in the seizure by militants of a school in North Ossetia, another nearby region.