Moscow, March 27, Thirteen children who died in a massive blaze that broke out at a shopping centre in Russia Kemerovo city, have been identified, Health Minister Veronika Skvortsova said on Tuesday.

A total of 64 people were killed in the fire that started on the top floor of the four-storey Zimnyaya Vishnya or Winter Cherry shopping mall on Sunday, engulfing an area of some 1,500 square metres.

"The bodies of 13 children who died in the fire have been identified," TASS news agency quoted the minister as saying.

Experts have started DNA tests required for identifying the bodies of those who died in the shopping center fire in Kemerovo, Veronika Skvortsova said.

"Forensic experts have arrived from Moscow, work on DNA tests has started," she said.

Skvortsova added that 25 bodies have already been identified and will be given to their relatives.

According to latest reports, 60 people were injured in the inferno out of which 15 were hospitalised and 40 received outpatient care.

The Kemerovo region will observe three days of mourning starting on Tuesday.

"The mourning will last for three days from March 27 to 29. The corresponding order was signed by Governor Aman Tuleyev. On the days of mourning, the state flags of the Russian Federation and the flags of the region will be lowered on the whole territory of the Kemerovo region," Xinhua news agency quoted an official statement as saying.

All institutions, organisations, TV and radio companies were asked to cancel recreational activities, it added.

Meanwhile, the head of the city's fire department Sergei Yakovlev said that the blaze had spread via flammable thermal insulation that complicated the process of extinguishing the inferno, reports Sputnik news.

The official cause is yet to be ascertained, although reports suggest that it could have been started by a child misusing a cigarette lighter or malfunctioning electrical wires.

Russia's Investigative Committee has launched a criminal investigation into the case, having reportedly arrested five suspects, including a private security company (PSC) employee who has switched off an alarm system in the mall.

"Serious violations were committed... Fire exits in the shopping centre were blocked," a Committee spokesperson said.