MAKHACHKALA, May 12 (RIA Novosti) - A police officer was killed overnight and three other people injured in a drive-by shooting in Russia's southern republic of Daghestan, a local Interior Ministry official said on Tuesday.

The spokesperson said the incident occurred on Monday evening near a town market in the Kizilyurt district, when gunmen opened fire on the police officer from a vehicle.

"The police officer died instantly, three people who were standing near the officer were wounded," he said.

A woman and two men have been hospitalized.

Investigators worked at the scene overnight and a search has been launched to try and trace the attackers.

Sporadic militant attacks and clashes remain common in Russia's North Caucasus republics neighboring Chechnya, although the Kremlin campaign to fight separatists and terrorists there was formally declared concluded. Violence often spills over into the republics, in particular Ingushetia and Daghestan.