RIA Novosti said it took firefighters more than two hours to extinguish the fire in the one-story building that housed workers who were constructing a new greenhouse.
Although earlier reports said six workers were killed in the fire, the regional emergency center said two more people were found during the clearing of debris.
The workers were from the Perm Region in the Ural Mountains, Ria Novosti reported, but the identities of the men had not yet being released.
The Russian news agency says the frequency of fires has risen drastically since the collapse of the Soviet Union, citing negligence, careless smoking and failure to comply with fire safety rules as among the main causes.
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