Sputnik news agency quoted an emergency services source as saying that 10 people have been injured as a result of "an explosion of an unidentified device" in a shop in the Russian city of St. Petersburg.
The blast has resulted in several people being evacuated from the area.
The blast occurred inside a locker of a grocery store at an entertainment complex, Sputnik news agency reported.
The police, bomb-disposal experts and rescuers have arrived at the scene and according to initial reports, authorities are treating the incident as a "potential mass homicide attempt". (ANI)