STORY: The fire took place in the early hours of the morning at Polygon, a multi-purpose recreation venue used as a cafe, nightclub and bar. Rescuers said 250 people were evacuated from the building.
State media cited investigators as saying the fire started after a man fired a flare gun indoors, setting the ceiling alight. Police have now detained a man in connection with the incident, the interior ministry said.
Most of those killed in the fire had been found in the smoking room, utility room and near the toilets, TASS reported, citing emergency services.
"As a result of the fire, 13 people died; the number of dead and injured is being clarified," the Investigating Committee said in a statement.
The fire was extinguished as of 7:29 a.m. (0429 GMT), according to the regional governor.
Russia's emergency ministry said it had not recently carried out a fire safety inspection of the premises due to its classification as a small business.