A gunman has opened fire on New Year revellers at a packed nightclub in Istanbul on Sunday, killing at least 39 people, including many foreigners, then fled the scene.
Some people jumped into the nearby Bosphorus waters to save themselves after the attacker opened fire at random in the Reina nightclub just over an hour into the new year.
The Hurriyet newspaper cited witnesses as saying the attackers shouted in Arabic as they opened fire.
"We were having fun. All of a sudden people started to run. My husband said don't be afraid, and he jumped on me. People ran over me. My husband was hit in three places," one club-goer, Sinem Uyanik, told the newspaper.
"I managed to push through and get out, it was terrible," she said, describing seeing people soaked in blood.
Interior Minister Suleyman Soylu said 15 or 16 of those killed were foreigners but only 21 of the bodies had so far been identified.
He said 69 people were in hospital, four of them in critical condition.
"A manhunt for the terrorist is underway. Police have launched operations. We hope the attacker will be captured soon," he told reporters.
Turkey is part of the US-led coalition against Islamic State and launched an incursion into Syria in August to drive the radical Sunni militants from its borders.
"As a nation, we will fight to the end against not just the armed attacks of terror groups, but also against their economic, political and social attacks," President Tayyip Erdogan said in a written statement.
"They are trying to create chaos, demoralise our people, and destabilize our country ... We will retain our cool-headedness as a nation, standing more closely together, and we will never give ground to such dirty games," he said.
The Reina club is one of Istanbul's best known nightspots, popular with locals and foreigners alike.
As many as 600 people were thought to have been inside when the gunman shot dead a policeman and civilian at the door, forced his way in and then opened fire.
Istanbul Governor Vasip Sahin said the attacker used a "long-range weapon" to "brutally and savagely" fire on people.
"I didn't see who was shooting but heard the gun shots and people fled. Police moved in quickly," Sefa Boydas, a Turkish soccer player, wrote on Twitter.
"My girlfriend was wearing high heels. I lifted her and carried her out on my back," he said.
Hurriyet quoted Reina's owner, Mehmet Kocarslan, as saying security measures had been taken over the past 10 days after US intelligence reports suggested a possible attack.
