At least 39 people were killed and dozens wounded when a gunman dressed as Santa Claus opened fire in a crowded Istanbul nightclub during a New Year’s Eve party, according to officials and reports.

As many as 600 people were partying at the packed Reina nightclub, celebrating the start of 2017, when the assailant began firing at police outside about 1:45 a.m., Turkish officials said.

The shooter then began randomly firing inside the building, which overlooks the banks of the Bosphorus Strait that divides the Turkish city.

Witnesses described a gunman spraying the crowds of panicked partygoers with bullets. Thumping music initially masked the mayhem.

People scrambled for cover — with some revelers reportedly jumping from the venue into the water to escape the carnage.

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At least 70 people were injured in what appeared to be the first major terror attack of the new year, officials said.

Of the 39 dead, 16 were foreign nationals, Vasip Sahin, the governor of Istanbul Province, said.

Sahin said a single attacker, armed with an assault rifle, killed a policeman and a civilian outside the club before entering and firing on groups of people inside.

People scrambled for cover — with some revelers reportedly jumping from the venue into the water to escape the carnage.

At least 70 people were injured in what appeared to be the first major terror attack of the new year, officials said.

Of the 39 dead, 16 were foreign nationals, Vasip Sahin, the governor of Istanbul Province, said.

Sahin said a single attacker, armed with an assault rifle, killed a policeman and a civilian outside the club before entering and firing on groups of people inside.

People scrambled for cover — with some revelers reportedly jumping from the venue into the water to escape the carnage.

At least 70 people were injured in what appeared to be the first major terror attack of the new year, officials said.

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Of the 39 dead, 16 were foreign nationals, Vasip Sahin, the governor of Istanbul Province, said.

Sahin said a single attacker, armed with an assault rifle, killed a policeman and a civilian outside the club before entering and firing on groups of people inside.

People scrambled for cover — with some revelers reportedly jumping from the venue into the water to escape the carnage.

At least 70 people were injured in what appeared to be the first major terror attack of the new year, officials said.

Of the 39 dead, 16 were foreign nationals, Vasip Sahin, the governor of Istanbul Province, said.

Sahin said a single attacker, armed with an assault rifle, killed a policeman and a civilian outside the club before entering and firing on groups of people inside.

People scrambled for cover — with some revelers reportedly jumping from the venue into the water to escape the carnage.

At least 70 people were injured in what appeared to be the first major terror attack of the new year, officials said.

Of the 39 dead, 16 were foreign nationals, Vasip Sahin, the governor of Istanbul Province, said.

Sahin said a single attacker, armed with an assault rifle, killed a policeman and a civilian outside the club before entering and firing on groups of people inside.

People scrambled for cover — with some revelers reportedly jumping from the venue into the water to escape the carnage.

At least 70 people were injured in what appeared to be the first major terror attack of the new year, officials said.

Of the 39 dead, 16 were foreign nationals, Vasip Sahin, the governor of Istanbul Province, said.

Sahin said a single attacker, armed with an assault rifle, killed a policeman and a civilian outside the club before entering and firing on groups of people inside.

People scrambled for cover — with some revelers reportedly jumping from the venue into the water to escape the carnage.

At least 70 people were injured in what appeared to be the first major terror attack of the new year, officials said.

Of the 39 dead, 16 were foreign nationals, Vasip Sahin, the governor of Istanbul Province, said.

Sahin said a single attacker, armed with an assault rifle, killed a policeman and a civilian outside the club before entering and firing on groups of people inside.

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People scrambled for cover — with some revelers reportedly jumping from the venue into the water to escape the carnage.

At least 70 people were injured in what appeared to be the first major terror attack of the new year, officials said.

Of the 39 dead, 16 were foreign nationals, Vasip Sahin, the governor of Istanbul Province, said.

Sahin said a single attacker, armed with an assault rifle, killed a policeman and a civilian outside the club before entering and firing on groups of people inside.

People scrambled for cover — with some revelers reportedly jumping from the venue into the water to escape the carnage.

At least 70 people were injured in what appeared to be the first major terror attack of the new year, officials said.

Of the 39 dead, 16 were foreign nationals, Vasip Sahin, the governor of Istanbul Province, said.

Sahin said a single attacker, armed with an assault rifle, killed a policeman and a civilian outside the club before entering and firing on groups of people inside.

People scrambled for cover — with some revelers reportedly jumping from the venue into the water to escape the carnage.

At least 70 people were injured in what appeared to be the first major terror attack of the new year, officials said.

Of the 39 dead, 16 were foreign nationals, Vasip Sahin, the governor of Istanbul Province, said.

Sahin said a single attacker, armed with an assault rifle, killed a policeman and a civilian outside the club before entering and firing on groups of people inside.

People scrambled for cover — with some revelers reportedly jumping from the venue into the water to escape the carnage.

At least 70 people were injured in what appeared to be the first major terror attack of the new year, officials said.

Of the 39 dead, 16 were foreign nationals, Vasip Sahin, the governor of Istanbul Province, said.

Sahin said a single attacker, armed with an assault rifle, killed a policeman and a civilian outside the club before entering and firing on groups of people inside.

“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 said.

Turkish journalist Urun Dirier tweeted what was reportedly security footage from inside the club.

It appears to show a man wearing a small Santa hat making his way across a nightclub floor surrounded by debris.

Sinem Uyanik described a bloody scene to The Associated Press and said she saw several bodies inside the club.

Her husband, Lutfu Uyanik, was wounded in the attack.

“Before I could understand what was happening, my husband fell on top of me,” she said outside Istanbul’s Sisli Hospital. “I had to lift several bodies from on top of me before I could get out.”

Her husband was not in serious condition despite his injuries.

Footage from outside the club showed ambulances with flashing lights and police pushing bystanders away.

The club is in a posh neighborhood known for its nightlife — and is close to a soccer stadium where recent suicide attacks killed dozens.

WNBA players Essence Carson, Chelsea Gray and Jantel Lavender were partying next door to the deadly shooting and were not hurt, Los Angeles Sparks coach Brian Agler confirmed.

Carson tweeted that she was “stuck inside of the club because of ‘terror’ shooting in Istanbul.”

“Praises to the most high,” the 30-year-old shooting guard said.

The athletes were among about two dozen WNBA players competing in Turkey during the offseason.

It was not immediately clear what became of the attacker — and a few witnesses said there may have been more than one gunmen.

The club’s owner, Mehmet Kocarslan, told Turkish newspaper Hurriyet that there was increased security at the club for the past week, because of warnings from “American intelligence.”

Turkish authorities issued a temporary gag order on reporting from the nightclub area.

Security measures and tensions were heightened in major Turkish cities during the New Year’s Eve celebrations, with police barring traffic near key squares in Istanbul and the capital Ankara.

More than 17,000 police officers — some also dressed as Santa — were on duty in Istanbul.

New Year’s Eve celebrations in predominantly Muslim Turkey often incorporate Christmas imagery and decorations.

Ankara and Istanbul were targeted by several attacks in 2016 carried out by ISIS and Kurdish rebels, killing more than 180 people.

Less than two weeks ago, the Russian ambassador to Turkey, Andrei Karlov, was fatally shot by an off-duty police officer as the envoy gave a speech in Ankara.

The country is still reeling from a failed coup attempt in July that left at least 265 people dead.

White House spokesman Eric Schultz said President Obama was briefed on the attack by his national security team and asked to be updated as the situation develops. Obama is vacationing in Hawaii week with his family.

White House National Security Council spokesman Ned Price says the attack on “innocent revelers” celebrating the new year shows the attackers’ savagery.

Price said the U.S. supports its NATO ally Turkey as both countries fight terrorism.

Turkey’s justice minister, Bekir Bozdag, vowed that the country would press ahead with its fight against violent groups.

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