A police officer died in hospital after a skirmish with two gunmen in Dagestan's capital earlier on Thursday, the southern Russian republic's interior ministry said.
Shapi Aligadzhiyev, commander of a SOBR special police unit, was wounded in his chest in Makhachkala, but killed one of the attackers when he returned fire.
Police are searching for the other gunman, who fled the scene.
The mainly Muslim republic of Dagestan has been plagued by instability afflicting other regions of Russia's North Caucasus, including Chechnya and Ingushetia.
Militant violence, organized crime, high unemployment and corruption have been rife in the impoverished region dependent on subsidies from Moscow.
An explosive device was discovered near a natural gas pipeline in Dagestan on Wednesday, which experts said was equivalent to 10 kilograms of TNT. The bomb was detonated by authorities on Thursday.
Gas supplies in the area were not disrupted.
MAKHACHKALA, November 26 (RIA Novosti)