At least 16 foreigners were among 39 people people killed in the gun attack on an Istanbul club during New Year festivities, Turkish Interior Minister Suleyman Soylu said on Sunday.
Soylu said in televised comments that of 21 victims who have been identified so far, 16 are foreigners and five are Turks. Another 69 people are being treated in hospital for their wounds.
Indicating that the attacker was still at large, Soylu said: "The search for the terrorist continues... I hope (the assailant) will be captured quickly, God willing."
An assailant believed to have been dressed in a Santa Claus costume opened fire at a nightclub in Istanbul during New Year's celebrations. The province's governor described it as a terror attack.
Gov. Vasip Sahin said the attacker, armed with a long-barreled weapon, killed a policeman and a civilian outside the club before entering and firing on people partying inside. He did not say who may have carried out the attack.
"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," Mr. Sahin told reporters.
Media reports said the assailant entered the Reina nightclub, in Istanbul's Ortakoy district, at 1-45 am, dressed in a Santa Claus costume.
Some customers jumped into the waters of the Bosporus to escape the attack, the report said.
NTV television said the assailant may still be inside the nightclub.
Police in riot gear and machine guns backed up by armored vehicle blocked the area close to the Reina night club, one of the most popular night spots in Istanbul in the amid heavy rain. Several ambulances flashing blue lights arrived on the scene, some taking wounded to Istanbul hospitals.
The attack occurred shortly after midnight in the club where an estimated 600 people celebrated New Year's eve. Several shocked revelers were seen fleeing the scene after the attack and the music fell silent.
The club is located close to recent suicide attacks that killed dozens near a soccer stadium.
Istanbul had already been under heavy security surveillance during the festivities, with police mounting machine guns and armored vehicles parked on the streets.
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 and others as street vendors, state news agency Anadolu reported.
Ankara and Istanbul have been targeted by several attacks in 2016 carried out by the Islamic State group or Kurdish rebels, killing more than 180 people.
White House condemns 'horrific' attack
The White House condemned the "savagery" of at least one gunman in Istanbul who killed at least 35 people and wounded 40 others as they celebrated the New Year, calling the attack "horrific."
The gunman reportedly dressed as Santa Claus shot dead a policeman and a civilian at the entrance to the Reina nightclub, one of the city's most exclusive party venues, before going on a shooting rampage inside, according to the authorities.
NTV television said many party-goers threw themselves into the Bosphorus in panic after the attack and efforts were under way to rescue them from the waters.
"The United States condemns in the strongest terms the horrific terrorist attack at a nightclub in Istanbul, Turkey, which has left dozens dead and many more wounded," National Security Council spokesman Ned Price said in a statement.
"That such an atrocity could be perpetrated upon innocent revelers, many of whom were celebrating New Year's Eve, underscores the savagery of the attackers."
Price added: "We reaffirm the support of the United States for Turkey, our NATO ally, in our shared determination to confront and defeat all forms of terrorism.
State Department deputy spokesman Mark Toner said the United States would be "in close touch" with Turkish authorities as they investigate the attack.
"Sadly, this heinous attack is only the latest effort to kill and maim innocent civilians," he added.
"These attacks only reinforce our strong determination to work with the Government of Turkey to counter the scourge of terrorism."
Santa' nightclub attack: What we know
Here is what we know about the attack, the latest to rock Turkey in a bloody 2016.
The venue 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.
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.
The attack 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 jihadists as well as Kurdish militants.
According to the NTV broadcaster, special forces officers were still searching the premises.
Terror in Turkey 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.
The attacks have been blamed either on Kurdish militants or the Islamic State jihadist extremist group.
The Turkish army is waging a four-month incursion in Syria to oust the IS group and Kurdish militants from the border area.
The toll 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.