Militants linked to Moscow bombings killed
The twin Metro suicide blasts left 40 people dead and more than 100 wounded.
The suspected militants were killed in a five-hour gun battle in the republic's capital, Makhachkala.
Security forces say the men, who were holed up in a house, opened fire after being asked to surrender.
Police found firearms and homemade explosives at the site.
Russia's south has seen a spike in terrorist attacks recently.
Just last week, seven people were killed and scores wounded when a bomb exploded near a concert hall in the city of Stavropol.