ISIS claimed responsibility on Jan. 2 for a New Year's Day mass shooting at a Turkish nightclub.
The shooting, perpetrated by a lone gunman who remains at large, claimed the lives of 39 victims in a packed Istanbul nightclub. ISIS says the attack was revenge for Turkish military involvement in Syria.
"The apostate Turkish government should know that the blood of Muslims shed with airplanes and artillery fire will, with God's permission, ignite a fire in their own land," the declaration said.
Turkish government spokesman Numan Kurtulmus acknowledged his government had angered terrorist groups with its intervention in Syria.
"This attack is a message to Turkey against its decisive operations across the border," Kurtulmus said during a news conference in Ankara.
Authorities say they are close to naming the gunman after acquiring fingerprints and gathering information about his basic appearance.
Police also released a blurry black-and-white picture of the suspect taken from a security camera. The gunman is believed to be from Central Asia and may belong to the same extremist sect that was responsible for the June 2016 attack on the Istanbul airport which left 45 people dead and hundreds wounded.
ISIS has been accused of more than half a dozen attacks in Turkey since 2015. Besides assassinations, this is the first attack in Turkey for which ISIS has claimed responsibility, according to Reuters.
Some blame Kurdish militants for the nightclub shooting. About 600 people were believed to be inside the club during the shooting. Witnesses say he fired with an automatic assault rifle and was shouting "Allahu Akbar" (God is Greatest).
The suspect was thought to have taken a taxi from the southern Zeytinburnu district of Istanbul and then got out to walk because of heavy traffic.
He reportedly retrieved a Kalashnikov rifle from a suitcase to use in the attack. As soon as he entered the Reina Club, he opened fired at those at the door and then threw two hand grenades after going in.
One of those wounded is an American who says he played dead to avoid being killed.
William Jacob "Jake" Raak, 35, from Greenville, Delaware, was visiting friends in Istanbul to celebrate his 35th birthday, USA Today reports.
"I was shot in the [expletive] leg, man," Raak said, who was lying on the ground when he was shot. "These crazy people came in shooting everything!"
"I just let him shoot me," he said. "You just have to stay as calm as you can ... I took a bullet."
His brother, Michael, told reporters Jake possibly avoided more serious wounds because the bullet originally hit Jake's cellphone.
"I was with nine people. Seven of us were shot," he said. "All I can say is it's a massive tragedy."
The U.S. Embassy in Ankara said on social media that U.S. officials had no knowledge of any specific target when it issued a general warning about travel to Turkey days before the blast.
"Contrary to rumors circulating in social media, the U.S. Government had no information about threats to specific entertainment venues, including the Reina Club," the embassy said in statement.