The fire Friday in the village of Perkhushkovo burned for five hours, said the duty officer for the Emergency Situations Ministry. It was extinguished after dark, and investigators began combing through the site only after dawn Saturday.
Seven people were hospitalized, the officer said.
Footage broadcast on NTV television showed the upper floors of the warehouse charred by smoke.
Investigators speculated that the fire resulted from work safety violations, the Interfax news agency reported.
Interfax, citing an unnamed source in the Moscow regional fire service, earlier reported 15 people were killed.
About 19,000 people died last year in fires in Russia, most of them blamed on negligence. The annual number of fire deaths in Russia is several times higher than in the United States or Britain.
