Russian security forces battled a group of suspected terrorists holed up in an apartment building in a troubled southern province Monday, officials and witnesses said.
The early morning siege on a house in the city of Cherkessk was the latest in a string of similar police operations across southern Russia, where violence has been rising, some of it having spilled over from war-wrecked Chechnya.
Authorities surrounded the apartment building where the four alleged militants were believed to be hiding and used heavy gun fire and grenades in a bid to force their surrender, regional police said.
Authorities had cordoned off nearby streets, closed a school in the neighborhood, but had been unable to evacuate all residents in the building, witnesses said.
Witnesses said smoke was rising from the apartment building but emergency officials denied the house was on fire. Police later said the smoke came from smoke grenades used by security forces.
The terrorists were suspected members of a group that was involved in killing local police officers, said Anna Lyzina, spokeswoman for the regional branch of the Federal Security Service, the KGB's main successor agency.
The suspected attackers were hiding in an apartment belonging to a key figure in the case of the murder of seven local businessmen in which the ex-son-in-law of the regional leader was implicated, an officer with the regional branch of the Interior Ministry told the Associated Press on condition of anonymity because he was not authorized to speak to the media.
The case sparked mass protests against the leader, Mustafa Batdyev, who was accused of covering up the crime, in which his former son-in-law, Ali Kaitov, was charged with murder. The slain businessmen were shareholders in a chemical company of which Kaitov was reportedly interested in acquiring greater control.
The apartment owner and a close friend of Kaitov, Temirlan Bastanov, was being held in custody and a regional court had been due to issue a verdict on him. Bastanov, was also charged with murder and prosecutors had asked to sentence him to life in prison.
Russia's North Caucasus has been hit by an increasing wave of violence, much of it blamed on criminal gangs and Islamic militants but also on fighting spilling over from Chechnya.