At least 39 people were killed when a gunman stormed a nightclub in Turkey where hundreds of revellers were celebrating the New Year.
The hunt continues for the attacker who opened fire with a long-barreled weapon on the Reina club in Istanbul, according to government officials.
Eight people have been arrested in connection with the attack, but the suspected gunman is not thought to be among them.
So-called Islamic State have claimed responsibility for the attack.
A number of foreign nationals are believed to be among the victims in what is the latest attack on Turkish soil in recent months.
The assault began outside the club, where a gunman - believed to have been dressed as Father Christmas - shot dead two people outside Reina nightclub in Istanbul.
A policeman and civilian were both killed.
Armed with what was described as a "long-barrelled weapon", the gunman then entered the club in the Ortakoy district and began shooting at revellers.
More than 500 people were inside the club - including foreign nationals - when the attack began at approximately 1.45am local time.
The gunman remains on the run with security forces on the hunt.
How did witnesses describe the attack?
One woman inside the nightclub said she saw several bodies.
Sinem Uyanik said: "Before I could understand what was happening, my husband fell on top me.
"I had to lift several bodies from on top of me before I could get out."
Istanbul's governor Vasip Sahin said: "He rained bullets in a very cruel and merciless way on innocent people who were there to celebrate New Year's and have fun."
Witnesses described police with riot gear and machine guns backed up by armored vehicles blocking the area close to the nightclub shortly after the attack.
Several ambulances with flashing blue lights arrived on the scene, some taking wounded to hospitals.
What are the numbers of the dead and wounded?
At least 39 people are said to have died in the attack - among those a number of foreign nationals. About 70 people were injured with many still being treated in hospital.
Turkish media reports seven Saudi nationals were killed.
France's foreign minister says one French citizen was killed and three others wounded.
The dead woman's Tunisian husband also died, Foreign Minister Jean-Marc Ayrault said.
The Israeli foreign office has named 19-year-old Leanne Nasser as being among the victims.
One Kuwaiti was also killed, a Kuwaiti diplomat to Turkey said.
Lebanon's foreign ministry confirmed three Lebanese citizens were among those killed, while Jordan said three Jordanians died. Four remained in hospital. Their conditions range from stable to critical.
The Foreign Office is attempting to find out whether any British nationals were injured in the attack at the club.
How has the world reacted?
Turkish interior minister Suleyman Soylu described the attack as a "terrorist."
He said: "This was a massacre, a truly inhuman savagery."
The White House condemned what it called a "horrific terrorist attack" and offered US help to Turkey.
White House official Ned Price said the attack on "innocent revellers" celebrating New Year's showed the attackers' savagery.
The attack on civilians celebrating the New Year in an Istanbul nightclub was the latest in a long line of assaults in Turkey in the past year.
Here are some of the most significant attacks:
January 12, Istanbul: A suicide bomber killed 12 German tourists in an attack that authorities said was linked to Islamic State (IS).
February 17, Ankara: A suicide car bomb apparently targeting military personnel killed 29 people. It was claimed by TAK, an offshoot of the Kurdistan Workers' Party.
March 13, Ankara: A Kurdish woman killed 37 people when she blew herself up in a car at a transport hub. It was also claimed by TAK.
June 28, Istanbul's Ataturk Airport: A trio of suicide bombers armed with assault rifles slaughtered 44 people and wounded nearly 150.
August 20, Gaziantep: A suicide bomber as young as 12 killed at least 51 people at a Kurdish wedding party in an attack suspected of being directed by IS.
December 10, Istanbul: A double bomb attack outside football stadium killed 44 people and wounded 149.
December 19, Ankara: A Turkish riot police officer assassinated Russia's ambassador to the country at a photo exhibition.