MOSCOW — Islamic gunmen staged coordinated attacks on police and government buildings in Russia's northern Caucasus region yesterday in a new wave of violence spilling over from war-torn Chechnya that killed more than 80 people.

Authorities said 12 police, 12 civilians and more than 50 guerrillas died in the day's fighting in Nalchik, capital of the predominantly Muslim republic of Kabardino-Balkaria. Seven more guerrillas were reported killed in an outlying district, and 17 were captured.

President Vladimir Putin ordered a total blockade of Nalchik to prevent militants from slipping out. He told security forces to shoot any armed resisters.

The fighting marked the continued spread through the region of the violence that started in the 1990s with a bid for independence by Chechen separatists.

"People have been talking for a long time now about the metastasis of the Chechen conflict throughout the North Caucasus, and this is one of the manifestations," said Nikolai Silayev, a Caucasus analyst at the Moscow State Institute for International Relations. "The situation in the North Caucasus is clearly not quieting down."

In September 2004, rebels seized a school in the town of Beslan, about 60 miles southeast of Nalchik; more than 300 hostages, police and rebels died in a firefight and explosions.

Russian First Deputy Interior Minister Alexander Chekalin estimated the number of rebels involved in yesterday's attacks at 100, but other officials said there could be up to 300 involved. Putin ordered a cordon to be put up around the city of 235,000 to prevent rebels from escaping.

"The president gave an instruction that not one gunman should be allowed to leave the town, and those who are armed and putting up resistance must be wiped out," Chekalin said in televised remarks after meeting Putin.

Mohammed Samukov, an aide to Nalchik's mayor, said fighting in the city began around 9 a.m., with attacks on three police buildings, a state security office, an anti-organized-crime unit and a border-guard detachment. The gunmen also tried to seize the city's airport, but failed, other authorities said.

Early today, security forces reportedly freed an unspecified number of police officers held hostage at a police station and stormed a store in search of other rebel holdouts. The ITAR-Tass news agency said there were three rebels in the store near the regional headquarters of the Federal Security Service and they were holding two hostages.

A doctor at City Hospital No. 2, who was willing to give only her first name, Galina, said that fighting had occurred near the hospital at midday.

"A group of several people was firing at our police, and they were warding off the attackers," she said. "The din was really something. There were explosions, but the hospital wasn't damaged."

Arsen Kanokov, president of Kabardino-Balkaria, said yesterday evening that the situation was under control.

"There is absolutely no panic. The entire state infrastructure is working, and all of the city's exit routes have been sealed off," he said.

Chekalin said security forces were searching for remaining rebels.

Alexei Malashenko, a Caucasus expert at the Carnegie Moscow Center, linked the incident to the ongoing military and political struggle in Chechnya between pro-Moscow and separatist forces, and to broad tensions between authorities and Islamists in the North Caucasus region.

In recent years, he said, authorities in Kabardino-Balkaria have sought to repress the expression of Islam outside of officially approved channels, and this appears to have produced a backlash.

"Relations between officials and believers deteriorated," Malashenko said.

Yesterday's attacks appeared to be an effort by Islamic rebels "to show everybody, including the Kremlin administration, that they are very strong and can do whatever they like, even in a big city like Nalchik," he said. "This was a kind of demonstration of their capacities. It is at the same time a certain revenge."

The attacks also could be a show of strength linked to a scheduled Nov. 27 parliamentary election in Chechnya.

Authorities blamed the attacks on a group called Yarmuk, which they said was linked to Islamic extremists and Chechen rebels led by Shamil Basayev and Abdul-Khalid Sadulayev.

Deputy Prosecutor General Vladimir Kolesnikov said in Nalchik that some of the captured rebels had begun to talk. He said the attacks were led by Islamic radicals Anzor Astemirov and Iless Gorchkhanov. They previously have been identified as leaders of Yarmuk and are wanted by police for allegedly masterminding an attack on the Nalchik drug-control office in December.

"Unfortunately, the aim of the bandit attack is to destabilize the situation and demonstrate their organizational, resource and other capabilities, and to try to show that the authorities are helpless when it comes to protecting public order and protecting citizens," Kolesnikov said.

A statement posted on the rebel-linked Web site Kavkaz Center also credited Yarmuk with Thursday's attacks.

Mindful of the Beslan attack, for which Basayev claimed responsibility, authorities in Nalchik said they evacuated children from schools. Los Angeles Times reporters Natasha Yefimova and Yakov Ryzhak contributed to this report.