A total of 51 people were provided medical treatment following the incident, according to Sputnik. Thirteen people were hospitalized, including an 11-year-old boy who remained in a grave condition, the Investigative Committee said in a previous statement.

The boy jumped out of a window from the fourth floor and suffered severe injuries, according to Skvortsova. The boy's parents lost their lives in the blaze, Skvortsova said.

The Winter Cherry shopping center, a business complex with a cinema, an indoor skating rink and a petting zoo, is usually packed with people on Sunday afternoon.

So far, five people have been detained and interrogated, including the head of the management company servicing the building and the tenants of the premises where the fire possibly started, the Investigative Committee said.

The investigators were checking information that emergency exits of the shopping mall were blocked when the fire broke out. It also remains undecided whether to detain a guard of the building, who allegedly disabled the warning system of the building.

The Prosecutor General's Office of Russia instructed regional prosecutors to conduct inspections of compliance with fire safety regulations in every shopping complex in Russian regions.

As yet, what caused the deadly blaze remains undetermined.

Several criminal cases were instituted on causing deaths by negligence and violation of fire safety requirements, according to the Russian Investigative Committee.

Russian President Vladimir Putin extended "deep condolences" to the families and friends of the victims on Sunday and ordered related authorities to provide all necessary help.

Kemerovo Regional Governor Aman Tuleyev has signed an order declaring mourning in the region from Tuesday to Thursday.