About 250 people were evacuated early on...
The flames have consumed over 1,000 sq. meters of the three-storey Opera night club and the roof of the club has collapsed, but no casualties have been reported at the site.
Over 30 firefighter teams with a variety of special equipment have been involved in efforts to extinguish the blaze.
"The spread of the flames has been stopped, although the fire has not been completely put out," Yevgeny Bobylev said.
"No casualties have been reported so far," he said, adding that two night guards and a club staff member were inside the building at the time the fire started, but they managed to leave the premises on their own.
According to officials, the operation of the Opera night club was suspended for 30 days in December last year due to poor fire safety record.
Nationwide fire safety checks were ordered by President Dmitry Medvedev after the deadly December 5 fire in a nightclub in the west Urals city of Perm had claimed at least 155 lives.