At least two people have been killed in the explosion of an automobile in a main city of Russia's restive North Caucasus region.

The state news agency RIA Novosti cited a spokeswoman for the regional Investigative Committee, Yekaterina Danilova, as saying two people were known dead in the Friday evening blast in Pyatigorsk.

The explosion took place near a traffic police station. News reports said investigators had not determined the cause of the blast and the victims had not been identified.

Bombings and other attacks occur frequently in the North Caucasus, where violence has spread following two separatist wars in Chechnya.

Pyatigorsk is the center of a federal administrative district created to oversee Kremlin efforts to stabilize the region, which is just east of Sochi, site of February's Winter Olympics.