Here is what we know about the attack, the latest to rock Turkey in a bloody 2016. The attack took place at the swanky Reina nightclub on the European side of the city. There were reportedly as many as 700 people dancing to celebrate the New Year, which chimed in barely an hour before the attack.
At least 35 killed in New Year gun attack at Istanbul nightclub
Situated in the Ortakoy district of Istanbul, the club is known as one of the most elite nightspots in the city and it is notoriously hard to get past the bouncers, who seek out only the best dressed. Television pictures showed shellshocked revellers dressed up to the nines -- men in suits and women in cocktail dresses -- emerging dazed from the scene.
The attack sparked mass panic, with some diving into the Bosphorus Strait between Europe and Asia to escape the bullets. Rescuers were battling to salvage them to safety. At least one gunman reportedly dressed as Santa burst into the nightclub, spraying bullets at random.
According to some witnesses cited by the Dogan news agency, the attackers were "speaking Arabic". The city's governor wasted no time as branding the bloodshed a "terror attack", the latest to strike Turkey after a wave of assaults by Islamic State militants as well as Kurdish militants.
According to the NTV broadcaster, special forces officers were still searching the premises. After a bloody 2016, the authorities were on their guard and at least 17,000 police officers were deployed in the city for the New Year festivities.
Turkey had enduring bomb attacks at an airport, a suicide bombing at a wedding and an attack near a top football stadium this year.
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The attacks have been blamed either on Kurdish militants or the Islamic State militant group. The Turkish army is waging a four-month incursion in Syria to oust the IS group and Kurdish militants from the border area. At least 35 people died and a further 40 were being treated in local hospitals, the city's governor said.
TV pictures showed ambulances ferrying the wounded from the scene as police cordoned off the area.
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