Two policemen were killed and two others wounded when unknown assailants opened fire on a police vehicle in Russia's North Caucasus republic of Daghestan.
The incident happened late on January 6 in the Khasavyurt district.
Local security officials said occupants of another vehicle opened fire on the police car on the Khasavyurt-Oktyarskoye road.
The press service for Daghestan's branch of the Interior Ministry said other police chased the car and fired on it, killing at least one of the attackers.
The search for the remaining attackers was under way.
Violence has been common in Russia's North Caucasus republics for years.
Criminal and militant groups remain active in the region despite the Kremlin's efforts to restore stability to the area.
Police and officials are regularly targeted in attacks.
Based on reporting by TASS and Interfax