Istanbul opened 2017 by reeling from another terrorist attack, this time aimed at tourists and the cultural elite of Turkey. ISIS claimed responsibility for a massacre at a trendy nightclub in which a gunman sprayed automatic gunfire, killing 39 people, more than half of whom were foreigners, and wounding dozens more. The radical Islamist terrorist then calmly changed clothes to slip away, leaving investigators with a difficult trail to follow, as ABC News reports this morning:

WATCH: Manhunt for Istanbul nightclub terror suspect; at least 39 killed, ISIS claiming responsibility: https://t.co/9Qy3y0n8AK pic.twitter.com/Hi4yVhMuAE

— Good Morning America (@GMA) January 2, 2017

A manhunt is underway in Turkey after a gunman went on a rampage in a crowded Istanbul nightclub during New Year’s Eve celebrations early Sunday morning, killed at least 39 people and injured at least 69 more, according to Turkish Interior Minister Suleyman Soylu.

The popular Reina club had attracted a diverse crowd of between 400 and 500 patrons from foreign countries as well as Turkey to ring in the new year before the attack by an apparently lone shooter at around 1:15 a.m, authorities said.

Turkish police said one gunman perpetrated the violence. Later, they released on social media photos of men whom they said were the Istanbul nightclub “attackers,” images which they said were of the men going through a passport check-in as they entered Turkey.

The gunman armed with what authorities described as a long-barreled weapon killed a policeman and a civilian outside of the club before “[raining] bullets in a very cruel and merciless way on innocent people” inside the club, according to Visip Sahin, the governor of Istanbul.

It could have been worse. Police found almost 200 expended casings at the scene, and they think they have a brief timeline for the terrorist:

The attacker was believed to have taken a taxi from the southern Zeytinburnu district of Istanbul and, because of the busy traffic, got out and walked the last four minutes to the entrance of the nightclub, newspaper Haberturk said.

He pulled his Kalashnikov rifle from a suitcase at the side of the road, opened fire on those at the door, then threw two hand grenades after entering, Haberturk said, without citing its sources. It said six empty magazines were found at the scene and that he was estimated to have fired at least 180 bullets.

That could be enough to find his trail. Turkish officials have told their local press that they believe the attacker was likely from the Central Asian nations of Uzbekistan or Kyrgyzstan, and that there are similarities between this attack and the June attack at Ataturk Airport. The fear is that the same cell may be responsible for both attacks, and remains intact to plan more of them.

ISIS called Turkey a “servant of the cross” in its message claiming responsibility:

The IS-linked Aamaq News Agency said the attack was carried by a “heroic soldier of the caliphate who attacked the most famous nightclub where Christians were celebrating their pagan feast.”

It said the man opened fire from an automatic rifle in “revenge for God’s religion and in response to the orders” of IS leader Abu Bakr al-Baghdadi.

The group described Turkey as “the servant of the cross.”

NBC’s Philadelphia affiliate covers the story of the only American wounded in the attack. Jake Raak went to Turkey to celebrate his 35th birthday, and his cell phone might have given him a surprise gift. Raak describes how he had to act dead, even to the point of taking the bullet without flinching:

“I was shot on the ground,” William Jacob Raak told NBC News. “He was walking on a bench above my head.”

Raak, who goes by the name Jake, said that he didn’t move after being wounded.

“I just let him shoot me,” Raak said. “You just have to stay as calm as you can … I took a bullet.”

Astute readers will note the similarities between this attack and the Orlando nightclub shooting earlier this year, in which ISIS-inspired Omar Mateen killed 49 people. Increased security at higher-value targets might be forcing ISIS to look for soft targets instead, especially nightclubs and other cultural gathering places. It would not be surprising to find out that this terrorist, like Mateen, might have patronized the club in the past and understood its layout. It’s yet another reminder that we need to improve our situational awareness and be prepared to defend ourselves, even at a time when we celebrate — and perhaps especially at that time.