On-Don, Feb 20, SPA -- Security forces stormed an apartment building in southern Russia Sunday, killing three suspected Muslim extremists who had barricaded themselves inside, law enforcement officials said. A heavy firefight broke out early Sunday morning, said an officer in the Interior Ministry department in Nalchik, the capital of Kabardino-Balkariya, where the day-old standoff came to an end. Security forces used grenade launchers to lob canisters of tear gas into the building before entering, he said. The forces broke down the metal door to the second-floor apartment but retreated due to a high concentration of gas as well as smoke from a fire that had broken out. Officers finally entered the apartment after the blaze was extinguished, finding three bodies. No information was immediately released as to the identities or nationalities of the three.