MOSCOW (Reuters) – A small army of pro-Chechen fighters launched a massive attack on police and army buildings in a town in Russia”s turbulent Caucasus on Thursday, in which dozens were reported killed including 50 of the attackers.

Regional officials quoted by Russian news agencies said that after a morning of mayhem in Nalchik, main city of the Muslim Kabardino-Balkaria region near rebel Chechnya, at least 12 local residents had been killed and 64 others wounded.

Itar-Tass news agency said Russian forces had killed 50 of the 150 gunmen involved in the coordinated attack. Moscow radio said 20 members of the security forces had also been killed.

Chechen separatists who have been fighting for independence from Russia for more than a decade quickly claimed responsibility for the assault on Nalchik, a town of about 280,000 people.

&#34Forces 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 (Islamist brigade),&#34 a statement on the Chechen rebel Web site www.kavkazcenter.com said.

Interfax said fighting was still going on at one police building while an FSB state security building was under sniper fire.

Regional prosecutor Yuri Ketov said the armed group had launched attacks on interior ministry buildings and the local FSB headquarters.

&#34We have brought in extra interior ministry forces and armored vehicles. Defense ministry troops have sealed off areas where operations are underway to disarm and eliminate the attackers,&#34 Ketov was quoted as saying by Tass.

&#34These were meticulously planned and synchronized attacks,&#34 a police source was quoted as saying by Tass which described the attackers as &#34religious extremists.&#34

The attacks posed a new challenge to President Vladimir Putin”s hardline policy on Chechnya. The Kremlin leader sent envoy Dmitry Kozak to Nalchik to investigate the circumstances of the attack.

Kabardino-Balkaria is a Muslim region in the Caucasus that borders the North Ossetia province where Chechen militants attacked a school in the town of Beslan in September 2004, resulting in the deaths of 331 people, half of them children.

&#34Fighting is going on everywhere. The attackers are trying to seize cars and burst their way out of the town,&#34 an unnamed military source was quoted as saying by Interfax at the height of the fighting.

&#34I just woke up when an explosion went off. I could see buildings were on fire. Buildings in the center are burning,&#34 a local man, who did not wish to be named, told Reuters by telephone. &#34I”ve heard grenades, machine guns, heavy machine guns,&#34 he said.

The armed group attacked police buildings, Russian army units based in the region and a gun store in simultaneous raids.

Tass quoted police as saying the small army of attackers had operated in 10 mobile groups, targeting five or six strategic points.

An attempt to seize the regional airport was beaten off, agencies said.

Though security forces said the attacks had been repelled by late morning, the fact that special forces and armored cars had been brought in suggested they saw a capacity for continuing violence in the hours to come.

In North Ossetia, scene of the Beslan school bloodbath, security forces were put on high alert.

Tass, quoting an emergency services source, said there had been &#34numerous civilian casualties&#34 in Nalchik and more than 30 ambulances were being used to ferry the wounded to hospital.

Chechen separatist leader Abdul-Khalid Sadulayev has tried to set up what he calls a &#34Caucasus front&#34 since he took over the leadership of the movement in March, and said attacks in other Muslim regions would be coordinated with those by his own forces.

The attack was reminiscent of an operation in June 2004 when pro-Chechen militants attacked police buildings in Nazran and effectively took control of Ingushetia — near to Kabardino-Balkaria — for several hours. About 60 people, many of them police, were killed in that attack.

At the height of the fighting, automatic firing resounded around the town and smoke rose from one of the main police buildings under attack.

Children were evacuated from a school nearby, the agency said.