People across the globe have made a point to make New Year’s Resolutions and reform their habits in the coming year, celebrating the end of a devastating year and looking onward to a fresh start. However, the lives of patrons at Istanbul’s Reina nightclub changed forever when they were met with an unshakeable tragedy: their cheerful celebrations were brought to a sudden halt when 39 people were killed and 69 were injured early Sunday morning, among them one police officer in the crowd of more than 700 people who had congregated at the club to ring in the New Year. The victims were from many countries around the world.

The patrons attempted many modes of escape, with some even allegedly jumping into the water nearby to elude the attacker who carried a “long-range weapon,” Vasip Sahin described to BBC. Sahin noted that the attacker “brutally and savagely carried out the incident by firing bullets on innocent people,” whose only intention was to “celebrate the New Year and have fun.”

At the venue located in the Ortakoy area of Istanbul, the attacker was reported as being clad in a Santa Claus costume, according to BBC. Some witnesses cite that there may have been two individuals involved at the scene, but police have released the photograph of only one suspect, taken from a video that has streamed on several news outlets. The name of the suspect has not been identified. Turkish authorities have arrested two additional suspects, both foreign nationals, at the Ataturk airport in relation to the attack, leading to a total of 16 people who have been arrested thus far in connection to the tragedy. Terrorist organization ISIS claimed responsibility for the attack in a statement posted to Twitter on Monday.

Due to the magnitude of the attack, the Turkish government has called for a media blackout for reasons of safety and security. Istanbul continues to be on high alert, with more than 17,000 police officers on duty. Despite the arrests made in relation to the crime, the killer is still considered at large.