President Vladimir Putin’s special envoy to the region, Dmitry Kozak, said on state television the militants had seized hostages in a police station on Thursday.
“There are clashes in more than two areas. It is at police station number three where, unfortunately, there are hostages. An operation is under way” to try to secure their release, Kozak said.
He described the attacks in Nalchik as an organized assault “on the law enforcement system of the city.”
The Russian interior ministry said armored vehicles and special forces troops were involved in efforts to subdue the attackers.
Arsen Kanokov, president of the Kalbardino-Balkario province where Nalchik is located, was quoted by ITAR-TASS news agency as saying most of those killed in fierce fighting were among the some 150 gunmen who launched the attacks.
The dead also included around a dozen local residents, Kanokov said, without specifying whether they were members of local law enforcement bodies or merely bystanders.
But police said there were dead and wounded among security personnel as well.
Kanokov said around 50 people wounded were receiving treatment in local hospitals.
Media reports said some 300 militants were involved in the attacks which targeted the local offices of the Russian FSB federal security service and the interior ministry.
Interfax news agency said the militants also attempted to attack the Nalchik airport but were thwarted, while RIA-Novosti said they attacked at least two police stations and a private store that sells weapons.
In an image reminiscent of last year’s Beslan school hostage siege, children were seen fleeing from a primary school building while gunfire erupted nearby and smoke hung over the area.
One girl who ran out of the school said armed men were firing inside, but security officials later made clear that armed police had entered the school to ensure its emergency evacuation due to its close proximity to the site of one of the buildings under attack.
Russian media said gunbattles occurred at a number of locations in Nalchik and the city center was saturated with security forces while gunfire could be heard nearby.
Police cars equipped with loudspeakers circulated in parts of the city advising local residents to evacuate the area.
A local journalist quoted by RIA-Novosti said the gunmen were dressed in civilian clothing and took advantage of panic to blend in with the local population, hiding weapons under their clothes as they changed locations, before opening fire again on security forces.
A statement posted on an Internet web site used regularly by the rebels said the attack was mounted by a unit of the Caucasus Front of the Armed Forces of the Chechen Ishkeria Republic.
The Kavkazcenter web site said the gunmen belonged to the “Yarmuk jamat of Kabardino-Balkaria.”
The attack, the most spectacular since Beslan in September 2004, was the latest in a series by Chechen rebels on Russian federal security installations in the volatile North Caucasus region where Chechnya is located.
Interfax quoted an official as saying that the attacks were in reprisal for the recent arrest in Nalchik of a group of Islamic radicals, whom the gunmen were attempting to free.
Large teams of Chechen rebels have carried out similar attacks in other cities in the region in the past with one of their key tactical objectives apparently being the acquisition of weapons from security personnel.
The Yarmak unit said to have launched the Nalchik operation was the target of a swoop by security forces in January, a month after militants seized weapons from the local offices of the anti-narcotics agency.
Russian troops and pro-Russian Chechen security forces have been fighting a war in Chechnya for the past six years, the second war there in a decade.
Russian officials insist the conflict is winding down and the situation normalizing, but Chechen rebels have vowed to keep up attacks in Chechnya and elsewhere in Russia until Russian forces leave the republic.