Those killed included the head of security of a regional division of Russia's gas giant Gazprom and a civilian who was shot dead in his front yard, reports quoted Dagestani security officials as saying.

Bodies of the four men with shots to the head were found by local villagers near the foothills that separate Dagestan from Chechnya.

One of the four men was a local policeman, the Interfax news agency reported.

Copyright AFP (Agence France-Presse), 2011