Atleast 35 people were killed and 40 wounded in a terrorist attack in Istanbul on Sunday.  A gunman dressed in a Santa Claus costume opened fire at a crowded nightclub in Istanbul during New Year’s celebrations.

Before entering the night club the gun man killed a policeman and a civilian outside the club at around 1:15 pm. The club, which was packed with a crowd of over 500 people on the eve of new year.

The city’s Governor Vasip Sahin termed the incident a “terror attack” but shed no light on who may have carried it out. “Unfortunately (he) rained bullets in a very cruel and merciless way on innocent people who were there to celebrate New Year’s and have fun,” he told reporters. Sahin said there was only one attacker but other reports, including on social media, suggested there may have been at least two.

The club popular with locals and foreigners alike, overlooks the Bosphorus Strait separating Europe and Asia in the Ortakoy district, a neighbourhood on the city’s European side nestled under one of three bridges crossing the Bosphorus and home to nightclubs, restaurants and art galleries. Some of the party-goers jumped into the waters of the Bosphorus to save themselves and were rescued by police.

Security measures had been heightened in major Turkish cities, with police barring traffic leading up to key squares in Istanbul and the capital, Ankara. In Istanbul, 17,000 police officers were put on duty, some camouflaged as Santa Claus or street vendors.

Turkey, a NATO member and part of the US-led coalition against Islamic State, faces multiple security threats including spillover from the war in neighbouring Syria. US President Barack Obama expressed condolences on Saturday for the attack at a night club in Istanbul and directed his team to offer help to their NATO ally. The White House condemned the “savagery”, calling the attack “horrific.”