Security forces in Dagestan have shot and killed the man suspected of organising of the Volgograd suicide bombings in December.
Russian security sources say Dzhamaldin Mirzayev, 30, and another man died after opening fire on security forces surrounding a house.
A third man surrendered during the siege in the town of Izberbash.
Thirty four people in the bomb attacks in Volgograd on consecutive days on 29 and 30 December.
The BBC reports the bombers, both male, were officially identified last week as Asker Samedov and Suleyman Magomedov, members of a group based in Buynaksk, a town in Dagestan.
Two men suspected of helping them were arrested in the region.
According to the Komsomolskaya Pravda newspaper, Samedov carried out the first bombing.
