"As of 08:00 (on December 28, 2017), the total number of people injured in the blast in a supermarket in Kondratyevsky Avenue is 13.
Of these, five refused to be taken to the hospital.
Five of those remaining in hospitals are in a moderately grave condition, while three are in a satisfactory condition," Russia`s news agency TASS reported, citing the city's Vice-Governor in charge of social issues, Anna Mityanina, as saying, in a Twitter post.
The incident, which occurred at the Perekrestok supermarket late on Wednesday, is being investigated as a "potential mass homicide attempt," the officials said.
Earlier reports had stated that the incident left ten persons dead.
There are reportedly no children among those injured.The explosion went off inside a locker of a grocery store.