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By Phil Helsel and The Associated Press

A gunman opened fire on an Istanbul nightclub crowded with revelers celebrating New Year’s early Sunday, killing 39 people wounding nearly 70 more in what is being described as a terror attack, Turkey’s interior minister said.

The attacker was still at large, Turkish Interior Minister Suleyman Soylu said Sunday. "Efforts to find the terrorist are continuing," Soylu said.

"Our security forces have started the necessary operations. God willing he will be caught in a short period of time," the minister said.

The attacker killed a police officer and a civilian before entering the popular Reina nightclub in Istanbul's Ortakoy district at around 1:15 a.m. local time, Istanbul Governor Vasip Sahin Sahin said according to state media Anadolu Agency.

"He then carried out this violent and cruel act by spraying bullets on innocent people who were celebrating the New Year," Sahin said according to Anadolu Agency. The attacker was carrying a "long barreled weapon," Sahin said.

Istanbul's governor said earlier that 35 were killed in the attack. Sixteen of the dead were foreign nationals, Soylu said, but nationalities were not released. Five of the victims were Turkish nationals and 18 have yet to be identified, he said. Sixty-nine people were being treated in hospitals, he said.

Ambulances transport wounded people after a gun attack on Reina, a popular night club in Istanbul near by the Bosphorus, early morning in Istanbul, Turkey on Jan. 1, 2017. STR / EPA

Special forces sealed off a 2-mile radius around the nightclub after the shooting. There were more than 500 people inside the club at the time, private NTV television reported.

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Sinem Uyanik was in the club with her husband, who was wounded in the attack.

"Before I could understand what was happening, my husband fell on top me," she told The Associated Press outside Istanbul's Sisli Hospital. "I had to lift several bodies from on top of me before I could get out."

U.S. President Barack Obama was briefed about the situation. "The President expressed condolences for the innocent lives lost," and instructed his team to offer appropriate assistance to Turkey, White House deputy press secretary Eric Schultz said.

National Security Council spokesperson Ned Price said the U.S. condemned the attack in the strongest possible terms.

An injured woman is carried to an ambulance from a nightclub where a gun attack took place during a New Year party in Istanbul, Turkey, January 1, 2017. Reuters

U.S. President Barack Obama was briefed about the situation. "The President expressed condolences for the innocent lives lost," and instructed his team to offer appropriate assistance to Turkey, White House deputy press secretary Eric Schultz said.

National Security Council spokesperson Ned Price said the U.S. condemned the attack in the strongest possible terms.

"That such an atrocity could be perpetrated upon innocent revelers, many of whom were celebrating New Year's Eve, underscores the savagery of the attackers," he said in a statement. Price reaffirmed U.S. support for Turkey, a NATO ally.

The Reina nightclub has been described as a trendy spot popular with the international crowd and frequented by celebrities. It is on shore of the Bosphorous strait.

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, state news agency Anadolu reported.

Ankara and Istanbul have been targeted by several attacks in 2016 carried out by ISIS 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.

Earlier this month two bombings near a stadium in Istanbul killed 38 people, mostly police officers, and injured 155 others. A Turkey-based Kurdish militant group claimed responsibility for that attack.

The. U.S. embassy in Turkey in an emergency message warned U.S. citizens to avoid the area and asked Americans to contact family members. It reminded Americans that extremist groups are continuing "aggressive efforts" to carry out attacks in places where U.S. citizens live or frequent.

The U.S. State Department said it would remain in touch with Turkish authorities during the investigation. High Representative for the European Union Federica Mogherini tweeted her condolences.

2017 starts with an attack in #Istanbul. Our thoughts are with victims and their loved ones. We continue to work to prevent these tragedies — Federica Mogherini (@FedericaMog) January 1, 2017

Cities around the world stepped up security in anticipation of New Year's and following the truck attack on a Christmas market in Berlin and other terror attacks.

The attack in Istanbul prompted the New York Police Department to deploy some counter-terrorism teams and patrols to nightspots, police officials said although they cautioned there were no specific or credible threats to the city.