Nalchik, Russia ? Militants attacked police and government buildings in Russia’s volatile Caucasus region Thursday, taking hostages and turning a provincial capital into a war zone wracked by gunfire and explosions that left at least 85 people dead, mostly insurgents.

Chechen rebels claimed responsibility for the offensive in Nalchik, the capital of the mostly Muslim republic of Kabardino-Balkariya, as a new front opened in the Kremlin’s decade-old battle against Islamic insurgents.

The rebels’ struggle against Russia, originally a separatist movement, increasingly has melded with Islamic extremism in the past decade and fanned out beyond Chechnya’s borders to encompass the entire Caucusus region.

The insurgent strategy of simultaneous attacks on facilities in Nalchik, a city of 235,000, was similar to a rebel siege last year in another Caucasus republic, Ingushetia, in what appears to be an attempt to target areas outside Chechnya and keep Moscow off-balance.

Kabardino-Balkariya is the fifth of seven republics in the mountainous region to be hit by the spillover of violence from the struggle in Chechnya. The insurgents are trying to exploit tensions among a variety of ethnic groups in the impoverished region as well as native Muslims and the ethnic Russians, who are Christian.

President Vladimir Putin, beleaguered by attacks that have killed hundreds of civilians and underscored his failure to bring the southern area under control, ordered a total blockade of Nalchik to prevent militants from slipping out. He told security forces to shoot any armed resisters.

Thursday’s fighting began about 8:30 a.m. Thursday after police launched an operation to capture about 10 militants in a Nalchik suburb. All 10 suspected militants were killed, Russian Deputy Interior Minister Alexander Chekalin said.

Gunmen staged simultaneous attacks against three police stations, the city’s airport and the regional headquarters of the Interior Ministry and Federal Security Service in what appeared what appeared to be an effort to divert police.

The militants also attacked the regional headquarters of the Russian prison system, the Emergency Situation Ministry’s press office said. Interfax said a border guards’ office also came under attack.

Police and security forces have fought pitched battles with militants across the region, and the rebels have employed terrorist methods including suicide bombings and the seizure of more than 1,000 hostages last year in a school in the town of Beslan, 60 miles southeast of Nalchik.