Authorities in Russia's southern republic of Chechnya say four people, including three policemen, have been killed near the Chechen capital, Grozny.
Russia's Itar-Tass news agency says the explosion occurred early Sunday, as police responded to gunfire apparently aimed at a policeman guarding an oil facility. Authorities say the blast, from a remote-controlled bomb, was triggered as police gathered at the scene of the shooting.
The Itar-Tass report says eight other people were wounded, including five policemen. No arrests have been announced.
Chechnya, a mostly Muslim region in southern Russia, has been devastated by two separatist wars since the 1990's. Major fighting subsided several years ago, but the region is still plagued by sporadic violence aimed at Russian forces and pro-Russian local authorities.
Some information for this report was provided by AFP, AP and Reuters.