Three militants, including one woman, were killed Wednesday in a special counter-terrorism operation in Russia's volatile north Caucasus republic of Dagestan, the National Anti-Terrorist Committee (NAC) said.

The police blocked the militants' apartment in the town of Khasavyurt in the Dagestan Republic, the NAC was quoted by Itar- Tass news agency as saying, adding that the two gunmen refused to surrender and fired at the police.

The woman, who is wife of one militant, refused to leave her husband and was killed in the special operation.

Meanwhile, the police evacuated the children of the militants through a fire-escape ladder.

The police also seized handguns, hand grenades and a large amount of ammunition in the apartment.

No policemen or civilians were hurt during the operation.

Russia has been plagued by terror attacks for years and many originated from the Caucasus region.

Violence is common in Russia's north Caucasus, especially in republics of Chechnya, Dagestan and Ingushetia, with militants frequently mounting attacks against police officers and authorities.

Russian President Vladimir Putin has urged the anti-terrorism forces to work "daringly and actively" to prevent possible terror attacks.