Police have blocked a group of gunmen hiding in a private house in Makhachkala, the capital of Russia's North Caucasus republic of Dagestan, a local police spokesman said on Sunday.
"Now an active phase of the operation is ongoing. The counterterrorist regime was imposed at about 7.30 a.m. local time [4.30 a.m. GMT]," the spokesman said.
He said the gunmen are suspected of killing of a policeman in Makhachkala on Thursday. The suspected assailants opened gunfire on a police patrol when they were stopped.
According to the National Anti-Terrorist Committee, more than half of all terrorist attacks in the North Caucasus in 2010 have occurred in Dagestan, RIA Novosti reported.