AKIPRESS.COM - ISIS claimed responsibility for the New Year's attack at Istanbul's Reina nightclub that left 39 people dead, but authorities are still scrambling to find the killer, CNN reports.

"In continuation of the blessed operations which ISIS carries out against Turkey, a soldier of the brave caliphate attacked one of the most popular nightclubs while Christians were celebrating their holiday," the statement read.

Turkish officials have called the attack an act of terrorism. Investigators have found the fingerprints of the suspect and know what he looks like, Deputy Prime Minister Numan Kurtulmus said Monday. 

Eight people have been detained in connection with the attack, Kurtulmus said, but the suspect was not among them.

"We will find him, no delay," Turkish Prime Minister Binali Yildirim said.

Footage of the attacker showed him shooting a security guard and police officer at the entrance of the nightclub. Turkish authorities said they believe he carried out the attack alone.

Those killed in the attack were from 14 countries, including India, Morocco, Jordan, Canada, Russia, Tunisia, Saudi Arabia and Kuwait.