NALCHIK, Russia - Scores of Islamic militants launched simultaneous attacks on police and government buildings in this city in Russia's turbulent Caucasus region today, sparking battles that killed at least 63 people.

Chechen rebels claimed responsibility for the attacks, which forced the evacuation of schools and left corpses littering the streets of Nalchik, the capital of the republic of Kabardino-Balkariya.

President Vladimir Putin ordered a total blockade of Nalchik, a city of 235,000, to prevent militants from slipping out, and he said armed resisters would be shot, according to Russian Deputy Interior Minister Alexander Chekalin.

Estimates of the number of militants involved ranged from 60 to 300. The attacks began with heavy arms fire and explosions, and sporadic shooting continued for four hours afterward.

Of the 63 killed, 50 were militants and at least 10 were police officers, Chekalin said. Local Health Ministry spokesman Stepan Kuskov said at least three civilians were among the dead, and 84 people were wounded. The ITAR-Tass news agency quoted a doctor at a city hospital, Asker Zhigunov, as saying 15 civilians' bodies had been brought in.

Dmitry Kozak, Putin's envoy to the southern region, said today's attackers were holding hostages at a police station, but he did not specify whether they were civilians or officers. A spokeswoman for the republic's Interior Ministry, Marina Kyasova, said police on the upper floors of the building were battling attackers on the ground floor, and denied that hostages had been taken.

The Chechen rebels' decade-long struggle against Russia, originally a separatist movement, has melded increasingly with Islamic extremism in the past decade and spread far beyond Chechnya's borders to encompass the whole turbulent Russian Caucasus region.

If the battles once shaped up between Russian troops and Chechen rebels, the picture has since grown far more complicated. Police and security forces have fought pitched battles with militants across the region, often engaging in urban warfare, 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, about 60 miles southeast of Nalchik.

The extremism is spreading despite the government's harsh anti-terrorist methods.

Chekalin said today's fighting began after police launched an operation to capture about 10 militants in a Nalchik suburb, and that the attacks were aimed at diverting police. All 10 suspected militants were killed, he said.

Gunmen launched simultaneous attacks against three police stations, the city's airport and the regional headquarters of the Interior Ministry and Federal Security Service.

The attack at the airport was repelled, the facility was placed under military control and all flights were canceled.

The militants also attacked the regional headquarters of the Russian prison system and a border guards' office also came under attack.