The Islamic State (IS) militant group has claimed responsibility for the deadly attack on a nightclub in Istanbul on New Year's Day that killed 39 people and wounded dozens of others.
The IS said in a statement on January 2 that a "soldier of the caliphate" had carried out the attack where "Christians celebrate their apostate holiday."
The Turkish dailies Hurriyet and Karar had reported earlier on January 2 that Turkish security officials suspected the IS was involved in the massacre. The newspapers also reported that the suspect was likely from Uzbekistan or Kyrgyzstan.
A manhunt continues in Turkey for the gunman, who escaped the scene.
Turkish authorities said they had arrested eight people so far.
A Turkish government spokesman said the authorities were close to fully identifying the gunman.
"Information about the fingerprints and basic appearance of the terrorist have been found. In the process after this, work to identify him swiftly will be carried out," Deputy Prime Minister Numan Kurtulmus told reporters on January 2.
He said Turkey's military incursion into Syria, launched in August, had annoyed terror groups and those behind them. But he said the offensive would continue until all threats to Turkey were removed.
Officials said 24 of the 39 people killed were foreigners. Sixty-nine people were wounded in the attack and four of them are reportedly in critical condition.
A source at the Russian Consulate in Istanbul told TASS that one of the victims was a Russian woman who had originally been identified as a citizen of Azerbaijan.
Other foreigners that have been identified among the killed include at least one Saudi citizen, a Canadian, at least two Jordanians, three Iraqis, three Lebanese, at least one Tunisian, two Indians, an Arab-Israeli, a Belgian-Turkish dual national, and one Libyan.
WATCH: Dozens Killed At Istanbul Nightclub On New Year's Day
The gunman killed a police officer and one other person at the entrance to the Reina nightclub in the city’s Ortakoy district about one hour after midnight.
Carrying an automatic weapon, he entered and opened fire on many of the 500 to 700 people in the upscale club who were celebrating the new year.
Several people reportedly jumped into the Bosphorus Strait to escape the gunfire.
Prime Minister Binali Yildirim has denied reports the attacker had worn a Santa Claus costume.
But the Associated Press reported that CCTV footage shows that the shooter wore a Santa hat for part of the attack.
Yildirim says the attacker left a gun inside the venue and escaped by "taking advantage of the chaos" that ensued.
Istanbul Governor Vasip Sahin described the attack as a "terrorist" incident.
"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," Sahin said.
Turkish President Recep Tayyip Erdogan said the attack was aimed at creating chaos in Turkey.
"They are working to destroy our country's morale and create chaos by deliberately targeting our nation's peace and targeting civilians with these heinous attacks," Erdogan said in a statement on the presidential website.
The Turkish government has imposed a media blackout regarding the attack, making an exception only for statements by government officials.
Security was high as the city was celebrating New Year’s. In Istanbul, some 17,000 police were reportedly on duty.
Istanbul and the Turkish capital, Ankara, were hit by numerous terrorist attacks in 2016. On December 10, 44 people were killed and 149 injured in a double bomb attack outside an Istanbul soccer stadium -- which is not far from the Reina nightclub.
In December, the IS released a video that purports to show the barbaric killing of two Turkish soldiers and then urging its fighters to "conquer" Istanbul. Turkish authorities did not confirm the authenticity of the video.