Turkish authorities were hunting for a lone gunman who opened fire on a New Year's celebration early Sunday at one of Istanbul's most popular nightclubs, killing dozens of people, many of them foreigners, and wounding scores more in one of the deadliest attacks on civilians in the city.
The victims include an Iraqi architecture student, a Turkish policeman and an Israeli woman celebrating the new year with her friends. At least 39 people were killed and 70 people wounded, and citizens of five other countries were believed to be among the dead, officials said.
Official say nationals of Saudi Arabia, Jordan, Morocco, Lebanon, Libya, Israel, a Turkish-Belgian dual citizen and a French-Tunisian woman were among those killed.
The assault, which began with a spray of gunfire from a single assailant around 1am, was the latest in a string of deadly attacks that have shaken Turkey as it faces threats both at home and from the civil war next door in Syria.
Sunday's incident was the fourth major attack in Turkey in less than a month, including the high-profile assassination of the Russian ambassador by a Turkish policeman, and a brazen car bomb attack against riot police at a soccer stadium in Istanbul. That attack was claimed by separatist Kurdish militants, who have waged a decades-long insurgency against the Turkish state.
Officials on Sunday called the nightclub attack a "massacre" and an act of terrorism. Turkish President Recep Tayyip Erdogan said the attack was meant to "trigger chaos."
We "will never give passage to these dirty games," Erdogan said in a statement posted on the presidency's website.
Turkish Interior Minister Suleyman Solu said the assault on the Reina Club - a sprawling venue on the edge of the Bosporus strait, popular with Istanbul's elite - was carried out by a single gunman who has not yet been identified. Speaking to reporters outside an Istanbul hospital, Soylu said the attacker changed clothes to escape the scene.
"Our security forces have started the necessary operations" to find the attacker, Soylu said. He said at least 15 of the 20 victims identified were foreign nationals. Later, Turkey's minister of family and social policies said that the victims included Saudi, Moroccan, Lebanese and Libyan citizens. Israel's Foreign Ministry confirmed that one Israeli woman, 19-year-old Leanne Nasser, was killed. Lebanese media also reported that one of its nationals was also confirmed dead.
The attack, which targeted a club popular with international clientele, appeared to echo the massacres at Bataclan, a Parisian concert venue, in 2015, and a gay nightclub in Orlando last June.
In both cases, one or more gunmen used assault rifles to shoot revilers at cosmopolitan venues in the heart of each city, killing scores from countries around the globe. Those attacks were claimed by the Islamic State. There has been no claim of responsibility, however, for the Istanbul attack.
Witnesses and officials described at least one gunman storming the club with a long-barrelled rifle, and stampedes of panicked patrons scrambling for cover at the waterside.
The assault began when the gunman shot and killed a police officer who was guarding the door, according to Istanbul Mayor Vasip Sahin, who spoke to reporters in front of the club about two hours after the shooting. After killing the policeman, the gunman "brutally and violently attacked innocent people who came here to enjoy themselves," Sahin said.
Sefa Boydas, a professional soccer player who was at the club, described the scene on Twitter. He said he did not see who was shooting but that the attack happened quickly. Police arrived soon after, he said, and he carried his girlfriend, who was wearing high heels, out of the club to safety.
The US Embassy issued a statement Sunday denying reports that the US government had information about threats to specific venues, including Reina. The nightclub's owner, Mehmet Kocarslan, had told the Turkish newspaper Hurriyet that there had been increased security at the club for a week or more, because of warnings from "American intelligence."
"The US Government did not warn Americans to stay away from specific venues or neighbourhoods," the embassy statement said.
Turkey's top cleric and head of the government's presidency for religious affairs, Prof. Mehmet Gormuz, also condemned the shootings Sunday, saying such an attack would be just as heinous if it took place in a mosque.
"The targets of terrorists are not places but the people, the country, the nation, and humanity overall," Gormuz said in a statement distributed by the prime minister's office. Such an attack, he said, "no Muslim conscience can accept."
The mass killing at the nightclub was at least the fourth major attack in Turkey in less than a month, raising questions about the ability of the government, a NATO member and critical regional ally of the United States, to counter threats stemming from the war across Turkey's border in Syria, as well as an escalating conflict with Kurdish militants inside Turkey.
At least one of the recent assaults - a suicide bombing at a soccer stadium in central Istanbul - was claimed by a Kurdish militant group. Authorities are still investigating who might have planned other attacks, including the December 19 assassination of Russia's ambassador to Turkey, by a police officer who denounced the carnage in Syria's civil war.
Turkey recently took a central role in trying to halt the hostilities in Syria, in coordination with Russia, which is allied with the government of Syrian President Bashar Assad. A recent cease-fire announced by Turkey and Russia was endorsed by several Syrian rebel groups but not others, including radical Islamist groups that might seek to retaliate against Erdogan's government because of its cooperation with Russia.
The attacks have come despite a widening security dragnet by authorities and a broad crackdown by the government on those whom officials have branded terrorists.
Ned Price, a White House National Security Council spokesman, released a statement condemning the attack.
"That such an atrocity could be perpetrated upon innocent revilers, many of whom were celebrating New Year's Eve, underscores the savagery of the attackers," the statement said.
President Obama was briefed on the assault and has "directed his team to offer appropriate assistance to the Turkish authorities," said Eric Schultz, White House deputy press secretary.
At the time of the attack, according to local media, hundreds of people were inside the club. Patrons reportedly jumped into the water to escape the gunfire, and dozens of ambulances could be heard heading in the direction of the club in Istanbul's Ortakoy district.
"We were there, we were having fun, when all of a sudden people started running," club patron Sinem Uyanik told Hurriyet. Uyanik was waiting outside a hospital, where her husband, who had also been at the club, was being treated for gunshot wounds.
"It was so horrible. It smelled like gunpowder," Uyanik said. At some point, she fainted, and then "woke up and saw my husband covered in blood," she told the paper.
"So many people were covered in blood," she said.
Security forces later stormed the nightclub, Uyanik said. Police in riot gear and armoured vehicles blocked the area around the venue, the Associated Press reported. Photos published by the state-run Anadolu news agency showed ambulances lined up outside the building.
Turkish authorities issued a temporary gag order on reporting from the scene. The order also barred media outlets from publishing any information on potential suspects, unless released through official statements.
Such bans are frequent in Turkey, where the government has embarked on a far-reaching crackdown on the news media. Still, images of the carnage circulated on social media early Sunday.