Pupils and teachers at a school near a police station in downtown Nalchik have been evacuated, a source in the security agencies said Thursday.
"Rumors about a school being seized do not correspond to reality," the source said.
"Armed attacks were carried out on three local police and Federal Security Service stations," an official of the presidential staff of the republic of Kabardino-Balkaria said.
The source in the security agencies said assaulters had tried to seize the airport but a Russian Defense Ministry company repelled the attack.
"Shooting can be heard all over the city, something explodes, and people are trying not to leave buildings," a local communal services official said, adding that mobile and some fixed communications had been disrupted.
The republic of North Ossetia, which borders on Kabardino-Balkaria, is reinforcing security measures.