At least one person was killed and seven people were injured in a blast that ripped through a railway station in Derbent town in the Russian North Caucasus republic of Dagestan Friday night, a police source said.
"According to the latest information, the number of wounded increased to seven," the source said adding that the number may rise further.
The explosive device was placed in a garbage dumpster near the platform, he said, adding that one of the hospitalised people is a police officer, who sustained grave wounds in the blast.
Russia's mainly Muslim North Caucasus republics, especially Chechnya, Dagestan and Ingushetia, have seen an upsurge of militant violence lately, with frequent attacks on police and officials.
The Kremlin has pledged to wage "a ruthless fight" against militant groups but also acknowledged a need to tackle unemployment, organised crime, clan rivalry and corruption as causes of the ongoing violence in the region.