Gunmen attacked a police headquarters and other government buildings, including school in a Russian province town near rebel Chechnya on Thursday and a battle was raging in the town, Russian news agencies reported.
Several simultaneous attacks were launched in Nalchik, main city of the Kabardino-Balkaria region, and fighting was going on in several parts of the town, Interfax reported, quoting local police.
News agencies had no details about the numbers of the attackers but described them as "religious extremists".
"At the present moment, federal forces have clashed with certain armed bands. Steps are being taken to eliminate the bandits," Nikolai Shepel, deputy state prosecutor for the region, was quoted as saying by Interfax.
Kabardino-Balkaria is a Muslim region in the Caucasus that borders the North Ossetia province where Chechen militants attacked a school in the town of Beslan in September 2004, resulting in the deaths of 331 people, half of them children.
Agencies said automatic firing resounded around the town and smoke was rising from the main police building that had come under attack, reports Reuters.
Interfax said that the battle was sparked by the detention of a group of adherents to the radical Wahhabi strain of Islam, and that their fellow believers were trying to free them.
It said that federal forces had surrounded Nalchik.
Kabardino-Balkariya, along with other southern Russian regions, has seen a rise in Islamic extremist movements and violence targeting police, soldiers and other law enforcement officials in recent years linked to the decade-old guerrilla conflict in the breakaway republic of Chechnya.
In December, gunmen raided the regional branch of the federal Drug Control Agency in Nalchik, killing four employees, looting an arsenal and setting the office ablaze.
Russian President Vladimir Putin has ordered security forces to deal more severely with suspected Islamic militants in the south. Law-enforcement agencies have launched a series of sweeps targeting suspected extremists outside Chechnya, reports the AP.