Authorities say the blaze erupted in the early hours of the morning, causing the roof of the venue to collapse. Rescuers were able to evacuate around 250 people.
At least 13 people were killed and five others were injured in a fire that broke out early Saturday at a bar in the Russian city of Kostroma, authorities said.
Initial reports said the blaze at the "Poligon" club may have been ignited by a flare gun.
"According to preliminary information, 13 people fell victim to the fire," Sergei Sitnikov, the local governor, said on Telegram.
Around 250 people were evacuated from the building, Russian news agencies reported.
Emergency services were called to the scene at around 2 a.m. local time (2300 GMT), and the blaze was put out by around 7:30 am.
The fire spread rapidly over an area of around 3,500 square meters, causing the building's roof to collapse.
Police are currently investigating the incident.
Kostroma, a city of around 230,000 people, lies some 300 kilometers (180 miles) northeast of Moscow.