Police on Sunday were hunting a Santa Claus-clad killer who opened fire at a nightclub in Istanbul during New Year’s celebrations, killing at least 39 people and wounding nearly 70 others, according to Istanbul’s governor and Turkey’s state-run news agency.

At least one policeman was stationed outside of the Reina nightclub when the attack occurred, but the gunman shot him and a civilian outside the club before entering and firing on people partying inside, Gov. Vasip Sahin said.

“Unfortunately (he) rained bullets in a very cruel and merciless way on innocent people who were there to celebrate New Year’s and have fun,” Sahin told reporters.

At least 15 of the dead were foreign nationals, Soylu said. Five of the victims were identified as Turkish nationals and others were reported to be from Lebanon, Morocco, Israel, Libya and Saudi Arabia.

“This was a massacre, a truly inhuman savagery,” Soylu said.

The owner of the nightclub initially said “American intelligence” had issued a warning at least a week before the attacks, however, the U.S. Embassy said no specific warning was given.

The attack occurred shortly after midnight in the club where an estimated 600 people celebrated New Year’s Eve. Several shocked revelers were seen fleeing the scene after the attack and the music fell silent.

The club is located close to recent suicide attacks that killed dozens near a soccer stadium. The nightclub area remained sealed off on Sunday morning.

Media reports said the assailant entered the Reina nightclub, in Istanbul’s Ortakoy district, at 1:15 a.m., dressed in a Santa Claus costume. Some customers jumped into the waters of the Bosporus to escape the attack, the report said.

Later in the evening, President Barack Obama expressed condolences for the attack and directed his team to offer U.S. help to Turkish authorities, the White House said.

The White House condemned the incident calling it a “horrific terrorist attack.”

President Recep Tayyip Erdogan also condemned “the terror attack in Istanbul’s Ortakoy neighborhood in the first hours of 2017” and offered condolences for those who lost their lives, including “foreign guests.”

“Turkey continues its combat against terror and is absolutely determined to do whatever is necessary in the region to ensure its citizens safety and peace,” the Turkish president said in a written statement on Sunday.

Russian President Vladimir Putin sent his Turkish counterpart a telegram of condolences, saying “it is hard to imagine a more cynical crime than killing innocent people during New Year celebrations.”

“However, terrorists don’t share moral values. Our common duty is to combat terrorists’ aggression,” Putin added.

Security measures had been heightened in major Turkish cities, with police barring traffic leading up to key squares in Istanbul and the capital Ankara. In Istanbul, 17,000 police officers were put on duty, some camouflaged as Santa Claus and others as street vendors, Anadolu reported.

Ankara and Istanbul have been targeted by several attacks in 2016 carried out by the Islamic State group or Kurdish rebels, killing more than 180 people.

Justice Minister Bekir Bozdag vowed that Turkey would press ahead with its fight against violent groups.

“Turkey will continue its determined and effective combat to root out terror,” Bozdag said on Twitter.

The Associated Press contributed to this report.