Security forces on Sunday stormed an apartment building in southern Russia (search) where a small group of suspected Islamic militants had barricaded themselves, killing all the rebels, police said.

A heavy firefight broke out early Sunday morning and security forces then entered the apartment building, said an officer in the Interior Ministry department in Nalchik, the capital of Kabardino-Balkariya, where the day-old standoff came to an end. He said it was not yet known how many militants had been in the apartment.

The alleged militants had been holed up inside a second-floor apartment in the latest in a series of confrontations between law-enforcement authorities and alleged extremists in the volatile North Caucasus (search) region, which includes Chechnya (search).

Last month, security forces killed seven alleged Islamic extremists in the same city in a two-day battle with members of the so-called Yarmuk group.

A duty officer at the southern district office of the Interior Ministry said Saturday that at least three suspects were inside the apartment.

He said the suspects were believed to be lightly armed, and discussions aimed at their surrender had been conducted Saturday. Russia's NTV television reported, however, that the suspects were refusing to negotiate.

Yarmuk is a radical Islamic group affiliated with Chechen warlord Shamil Basayev. It was blamed in a December attack on an office belonging to the Federal Drug Control in Nalchik, when raiders killed four of the agency's employees, looted its arsenal and set the office ablaze.

Russia's southern provinces have been plagued by a spillover of violence from Chechnya, including the September school hostage-taking in the city of Beslan in which some 330 people were killed.