Officials said at least one gunman reportedly wearing a Santa costume murdered a police officer and a civilian outside Istanbul’s famed Reina nightclub before bursting inside.
The attacker opened fire into the crowd of up to 700 people, killing at least 35 – including 15 foreigners – and injuring dozens more in the Ortakoy district.
Interior minister Suleyman Soylu said the attacker was still at large and 69 people were being treated in hospital following the shooting.
"Efforts to find the terrorist are continuing," he said. "Our security forces have started the necessary operations. God willing he will be caught in a short period of time."Local reports said some people jumped into the waters of the Bosphorus strait to escape the massacre, which started shortly before 1.30am local time (11.30pm GMT).
One survivor said she had to climb out from beneath bodies inside the nightclub to flee the attack, where her husband was injured.
“Before I could understand what was happening, my husband fell on top me,” Sinem Uyanik told the Associated Press outside Istanbul's Sisli Hospital. “I had to lift several bodies from on top of me before I could get out.”