Among the dead at the Istanbul club is one police officer, Vasip Sahin stated, adding that it was a terror attack.
At least another 40 were injured in the attack which took place in the Reina nightclub, in the Ortakoy area, at about 01:30 local time (22:30 GMT).
One attacker was involved, the governor said, while CNN Turk reported he was dressed in a Santa Claus costume.