Russian emergency officials said at least 13 people were killed when a fire erupted in a nightclub northeast of Moscow.
Law enforcement officials said on November 5 that the overnight blaze may have erupted after a fight broke out at the club in Kostroma and someone used a flare or similar pyrotechnic device.
Aleksei Grekov, deputy head for the Kostroma regional Emergencies Ministry, said the death toll was confirmed at 13, down from 15 reported earlier in the day.
Dozens of people were hospitalized and at least four were in intensive care, officials said.
The federal Investigative Committee said it was looking into whether the fire was caused by negligence. Police later said they had detained a man who allegedly started the blaze.
Russian news agencies earlier reported that the fire may have started after someone fired a flare gun on the dance floor.
Some 250 people were evacuated from the building when it caught fire at night in the city, which is some 300 kilometers northeast of Moscow.
The blaze at the Poligon club was put out at around 7:30 a.m. local time, authorities said, after spreading to more than 3,500 square meters.
State television showed images of the club -- housed in a single-story logistical center -- engulfed in flames.
Kostroma is located on the Volga River and has a population of around 230,000 people.