Russian authorities say at least four people have been killed in a series of bombings and shootings across the country's restive North Caucasus region.

In Dagestan, an officer with Russia's Federal Security Service was killed Thursday when a bomb blew up his car in the town of Khasavyurt. At least three female family members, who were travelling with him at the time, were wounded in the blast.

Elsewhere, a spokesman for the regional Interior Ministry says a senior police officer was killed in the republic of Kabardino-Balkaria, after unidentified gunmen attacked his car late Wednesday.

Also, a homemade bomb exploded, killing two people in Nazran, the capital of Ingushetia.

Russia's North Caucasus is beset by persistent violence linked to an Islamist insurgent movement. Chechen separatists fought two wars against Russia in the 1990s. Although major fighting has ended in the North Caucasus, attacks on police and government targets in the region continue, particularly in Dagestan.