The club was packed with guests celebrating the New Year when the attack occured.
Istanbul governnor Vasip Sahin called the incident a terror attack and said one police officer was among the dead.
Local media reports said several foreign nationals were among the wounded.
The attacker is described as a terrorist who used a “long-range weapon” to brutally and savagely shoot revelers.
According to VOA, “witnesses said as many as 600 people were inside at the time of the attack and said some revelers jumped into the waterway to escape the gunfire.”
Private NTV television said at least one gunman is believed to have gained entry to the club dressed as Santa Claus.
This is a breaking news story; updates to follow.
(With information from VOA)