A local police source said a suicide bomber detonated his car laden with explosives outside the traffic police headquarters in Makhachkala, the capital of Dagestan.

The blast completely destroyed the building's alert center, a spokesman for Dagestan's law enforcement services was quoted by Interfax.

Senior officials of Dagestan's Interior Ministry and investigators are working at the scene.

Dagestan and the other primarily Muslim regions of Russia's Northern Caucasus have recently been plagued by instability and violence. Skirmishes between troops and militants, as well as attacks on police and other officials have been reported daily.