Meanwhile, Turkish police detained eight people in connection to the attack but were still hunting for the gunman who disappeared amid the chaos of the attack.
The IS-linked Aamaq News Agency said the attack was carried out by a "heroic soldier of the caliphate" who attacked the nightclub "where Christians were celebrating their pagan feast."
Raak was visiting friends in Istanbul but is set to return home from overseas later Monday. According to his brother, Raak’s cellphone saved his life. A flying bullet hit that iPhone.
He explained what he witnessed while on a stretcher, being put into an ambulance.
"It's crazy. People came in started shooting up the place. I don’t know. I only saw one shooter. I'm there hiding you know," Raak said.
Unfortunately, from the iPhone, the bullet went from his hip and then his knee. Fortunately, it didn't break any bones or hit any arteries. The bullet was removed from Raak’s knee and his plan is to return home.
Raak lives in Greenville, Delaware, and runs a small business in Delaware County, Pennsylvania. He’s originally from Chadds Ford.
Turkey's state-run Anadolu Agency said eight people were taken into custody by Istanbul anti-terrorism squads and they are being questioned at Istanbul's main police headquarters. It did not provide further information on the suspects.
Earlier, Turkish media reports had said that Turkish authorities believed the IS group was behind the attack and that the gunman, who is still at large, is likely to be either from Uzbekistan or Kyrgyzstan.
According to the Hurriyet and Karar newspapers, police had also established similarities with the high-casualty suicide bomb and gun attack at Istanbul's Ataturk Airport in June and was investigating whether the same IS cell could have carried out both attacks.
The gunman killed a policeman and another man outside the Reina club in the early hours of 2017 before entering and firing with an automatic rifle at an estimated 600 people partying inside.
Nearly two-thirds of the dead in the upscale club, which is frequented by local celebrities, were foreigners, Turkey's Anadolu Agency said. Many of them hailed from the Middle East.
Citing Justice Ministry officials, Anadolu reported that 38 of the 39 dead have been identified. The report said 11 of them were Turkish nationals, and one was a Turkish-Belgian dual citizen.
The report says seven victims were from Saudi Arabia; three each were from Lebanon and Iraq; two each were from Tunisia, India, Morocco and Jordan. Kuwait, Canada, Israel, Syria and Russia each lost one citizen.
Relatives of the victims and embassy personal were seen walking into an Istanbul morgue to claim the bodies.
Turkish officials haven't released the names of those identified.
The mass shooting followed more than 30 violent acts over the past year in Turkey, which is a member of the NATO alliance and a partner in the U.S.-led coalition fighting against the Islamic State group in Syria and Iraq.
The country suffered multiple bombings in 2016, including three in Istanbul that authorities blamed on IS, a failed coup attempt in July and renewed conflict with Kurdish rebels in the southeast.
The Islamic State group claims to have cells in the country. Analysts think it was behind suicide bombings last January and March that targeted tourists on Istanbul's iconic Istiklal Street as well as the attack at Ataturk Airport in June, which killed 45 people. Authorities have said the three suicide bombers in the airport attack were Russia, Uzbekistan and Kyrgyzstan and there has been speculation that Akhmed Chatayev, a Chechen extremist known to be a top lieutenant in the IS militant group, may have directed the attack.
In August, Turkey sent troops and tanks into northern Syria, to clear a border area from the IS and also curb the territorial advances of Syrian Kurdish forces in the region. The incursion followed an IS suicide attack on an outdoor wedding party in the city of Gaziantep, near the border with Syria, that killed more than 50 people.
In December, IS released a video purportedly showing the killing of two Turkish soldiers and urged its supporters to "conquer" Istanbul. Turkey's jets regularly bomb the group in the northern Syrian town of Al-Bab. Turkish authorities haven't confirmed the authenticity of the video.
Last week, Turkey and Russia brokered a cease-fire for Syria that excludes the IS and other groups considered to be terrorist organizations.
On Monday, Anadolu said more than 100 Islamic State targets in Syria have been hit by Turkey and Russia in separate operations.
Citing the Turkish Chief of General Staff's office, Anadolu said Turkish jets struck eight IS group targets while tanks and artillery fired upon 103 targets near Al Bab, killing 22 extremists while destroying many structures. The Russian jets also attacked IS targets in Dayr Kak, eight kilometers (five miles) to the southwest of Al Bab.
Prime Minister Binali Yildirim said the attacker left a gun at the club and escaped by "taking advantage of the chaos" that ensued. Some customers reportedly jumped into the waters of the Bosporus to escape the attack.
The deadly New Year's assault on an Istanbul nightclub follows a long string of attacks in Turkey over the past year. A look at the most significant attacks:
-- Jan. 12, 2016, Istanbul: Suicide bomber kills 12 German tourists in historic district. Authorities say attacker was linked the Islamic State group.
-- Feb. 17, Ankara: A suicide car bomb apparently targeting military personnel kills 29 people in an attack claimed by TAK, an offshoot of the Kurdistan Workers' Party.
--March 13, Ankara: Kurdish woman blows herself up in a car at a busy transport hub, killing 37 people in an attack claimed by TAK, also known as the Kurdish Freedom Falcons.
-- March 19, Istanbul: Turkish suicide bomber kills five people in the city's main pedestrian shopping street, Istiklal. Turkish officials say bomber was linked to IS.
-- March 31, Diyarbakir: Car bomb kills seven police officers and wounds 27 people, including 13 police.
-- April 12, Gaziantep: Syrian journalist dies from gunshot wounds from attack claimed by IS.
-- April 27, Bursa: Female suicide bomber wounds 13 in a historic district of Turkey's fourth largest city.
-- May 1, Gaziantep: Car bomb at the entrance of a police station kills two officers, 22 other people wounded.
--May 10, Diyarbakir: Car bomb strikes police vehicle carrying officers escorting seven detained Kurdish militants, killing three people and wounding 45 others.
-- May 12, Istanbul: Car bomb targeting a military garrison explodes during rush hour, wounding eight people.
-- June 7, Istanbul: Car bomb hits a riot police bus during the morning rush hour, killing 11 people and wounding 36. A Kurdish militant group claims responsibility.
-- June 8, Midyat: Kurdish suicide car bomber kills five people and wounds 51, including 23 civilians, outside a police headquarters near Turkey-Syria border.
-- June 17, Istanbul: Car bomb explodes as a police vehicle passes by, killing 11 people.
-- June 28, Istanbul's Ataturk Airport: Three suicide bombers armed with assault rifles storm airport, killing 44 people and wounding nearly 150.
-- July 15: About 270 people die in military coup attempt.
-- Aug. 17, Van: Car bombing at a police station kills a police officer and two civilians; 53 civilians and 20 police officers wounded.
-- Aug. 18, Elazig: Car bomb at police headquarters kills at least five people and wounds more than 140.
-- Aug. 20, Gaziantep: Suicide bomber -- possibly as young as 12 -- kills at least 51 people at an outdoor Kurdish wedding party. IS suspected of directing attack.
-- Aug. 26, Cizre: Kurdish suicide bomber rams an explosives-laden truck into a police checkpoint, killing at least 11 officers and wounding 78 other people.
-- Sept, 12. Van: Car bomb wounds 50 people outside ruling party's municipal headquarters.
-- Oct. 6, Istanbul: Motorcycle bomb explodes near a police station, wounding at least 10 people.
-- Oct. 8, Ankara: Two suicide bombers blow themselves up after refusing to surrender to police. No one else was hurt.
-- Oct. 9, Hakkari province: Kurdish militants detonate car bomb outside a military checkpoint in the southeast, killing 10 soldiers and eight civilians.
-- Oct. 10, Dicle: A top local official of the ruling Justice and Development Party is killed when attackers open fire at a gas station he owned.
-- Nov. 4, Diyarbakir: Car bomb near a riot-police bus kills at least 11 people, including two police officers. A Kurdish militant group and IS both claim responsibility.
-- Nov. 24, Adana: Car bomb targeting a government building kills at least two people and wounds 33 others.
-- Dec. 10, Istanbul: A double bomb attack outside soccer stadium kills 44 people and wounds 149.
--Dec. 17, Kayseri province: Suicide car bomber targeting a public bus transporting off-duty soldiers kills 13 troops and wounds 56 other people.
--Dec. 19, Ankara: A Turkish riot policeman assassinates Russian Ambassador Andrei Karlov at a photo exhibition.
--Jan. 1, 2017, Istanbul. An assailant opens fire at a crowded nightclub during New Year's celebrations. Istanbul's governor says the attack killed at least 39 people and wounded 69 others.