Two police vehicles were targeted in explosions that were detonated just 30 minutes apart on Wednesday morning in the town of Khasavyurt in Daghestan, the police source said.
A criminal investigation has been opened into the blasts, the source said.
The first bomb went off on the outskirts of Khasavyurt near a road bridge injuring a police officer, who was hospitalized. The explosive, which was detonated by a remote-controlled device, contained the equivalent of one kg of TNT.
Thirty minutes later when a police team arrived at the scene a second blast was detonated hitting a second police vehicle and injuring five officers. Four other officers suffered shock in the blast, the source said.
Daghestan and Ingushetia, which both border Chechnya, have seen a sharp increase in attacks on law enforcement and military personnel of late.