Turkish media reports say an armed man opened fire on people taking part in new year celebrations at the Reina nightclub in the city's Besiktas neighbourhood.
Another 40 people are reported to have been wounded 
in the attack at the night spot, located by the Bosphorus and known to be a haunt of the city's elites.
Vasip Sahin, governor of Istanbul, said the incident 
was "a terror attack" targeting innocent people who
 were at the club to celebrate the new year.
Hundreds of people were believed to have been at the 
Reina when the attack occurred.
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