At least 85 people were killed in street fighting in the southern Russian city of Nalchik on Thursday morning after large groups of gunmen assaulted government buildings, telecommunications facilities and the airport. Chechen rebels asserted responsibility for the attacks.

Pitched battles across the city subsided by the early afternoon, but police continued to hunt for gunmen, officials said.

The city of 280,000 people is the capital of Kabardino-Balkaria, a small, autonomous republic that has become increasingly restive as violence spills across the region from nearby Chechnya, scene of a decade of war by Muslim rebels seeking independence.

"Forces of the Caucasus Front -- a unit of the Chechen Republic's Armed Forces -- went into the town, including attack brigades from the Kabardino-Balkarian Yarmuk," or Islamist Brigade, said a statement on Kavkazcenter, a Chechen rebel Web site.

The dead included 12 civilians and 12 members of the security forces, according to local officials and Russian news agencies. Deputy Interior Minister Andrei Novikov said late Thursday that 61 militants had been killed, the Associated Press reported. In addition, more than 100 people were wounded, according to local hospitals. Police said they captured 12 insurgents.

Estimates of the number of attackers ranged from 60 to 300. The uncertainty revealed a measure of the violence that descended on the city shortly after 9 a.m.

President Vladimir Putin ordered a complete blockade of Nalchik to prevent people involved in the attacks from escaping. "The president has ordered us to keep every militant within Nalchik and to eliminate any armed person resisting detention," First Deputy Interior Minister Alexander Chekalin said after a meeting with Putin.

The assault was one of the most intense in the region since an attack on multiple targets in another Russian republic, Ingushetia, in the summer of 2004. Ninety-two people were killed and police armories were looted.

The scale of Thursday's assault is likely to renew fears that a large swath of southern Russia is being destabilized by a toxic brew of Islamic radicalism, government repression, economic despair and endemic corruption. There are now almost daily reports of attacks on politicians, the military, police and security officials in the region.

Once a quiet republic that drew tourists to its excellent skiing, including slopes on Russia's highest mountain, Mount Elbrus, Kabardino-Balkaria has become increasingly unstable. On Wednesday, police said they had captured a large cache of explosives and weapons outside Nalchik and killed 10 radicals in a separate operation.

Putin's special envoy to the region warned in a leaked report this summer that the North Caucasus region, which includes Kabardino-Balkaria, risked becoming a "macro-region of sociopolitical and economic instability." Last month, Putin said that "the continuing activity of terrorist formations and other extremist groups is seriously destabilizing" the region.

Alexei Malashenko, an analyst at the Carnegie Moscow Center, said the attacks might have also resulted from divisions among Islamic radicals over the possibility of dialogue with the republic's new president, Arsen Kanokov, who was nominated by Putin and approved by the local parliament on Sept. 28.

A wealthy businessman with major interests in Moscow, Kanokov has said there must be a change in the republic's policy toward Islam. All but officially sanctioned versions of Islam were repressed under Kanokov's predecessor, Valery Kokov, who closed mosques and labeled dissidents "Wahhabis," a common Russian shorthand for Islamic extremists.

Local religious leaders had complained that the security forces were blindly targeting religious Muslims as likely extremists, spawning the very militancy the government is trying to combat.

"Under the pretext of the fight against extremism, they are prepared to include among the Wahhabis anyone who wears a beard or a veil or prays," Anas Pshikhachev, chairman of Kabardino-Balkaria's Spiritual Board of Muslims, said in the Russian magazine Kommersant-Vlast this month. "We have very cold relations with the law enforcement organs."

Kanokov's statement drew a positive response from Jammat of Kabardino-Balkaria, a Muslim group that had broken with the local Muslim establishment. Jammat said it would like Kanokov to reopen some mosques as a first step.

The possibility of some kind of accord with the republic's leadership was rejected, however, by a more radical organization, Yarmuk Jamaat, which has been linked to previous attacks in the republic and is allegedly allied with extremists in Chechnya.

"They were afraid of this dialogue," said Malashenko of the Carnegie Center. "If it takes place, the position of the extremists will be weakened. They saw the dialogue as a provocation."

Guerrillas launched almost simultaneous attacks after 9 a.m. Thursday on three police stations, the main Interior Ministry building and the local headquarters of the Federal Security Service, officials said. Residents said armed men dressed in civilian clothes suddenly appeared on downtown streets and began shooting as people scattered in panic.

Desperate parents tried to evacuate students from a school near some of the most intense fighting. A cell phone base station was blown up, police said, cutting off some communications with the city. Nalchik airport was closed after rebels failed to seize it, officials said.

Russian soldiers stand guard near Nalchik, in southern Russia, where attackers staged gun battles with troops in the streets.