A blast in Russia's restive North Caucasian republic of Dagestan on early Sunday derailed 16 cars of a cargo train, with no casualties reported so far.

According to the regional law enforcement authorities, the explosion hit the railways beneath the locomotive at around 04:15 a.m. Moscow time (0015 GMT), overturning the Derbent-bound train loaded with grain.

An investigation was currently underway.

North Caucasus Railways said suburban train traffic was suspended due to the blast, but passenger trains continued operation without delays.

Two weeks ago, a blast derailed 14 cars of a cargo train at the same railroad, injuring the train driver and his assistant.

Also on Sunday in the republic capital of Makhachkala, two policemen were wounded in a car explosion at the Akushinsky avenue near the entrance of a cemetery.

Violence is common in Russia's mainly Muslim North Caucasus republics, especially Chechnya, Dagestan and Ingushetia, with militants frequently targeting police and officials as representatives of Russian authorities.