ISTANBUL -- Police on Thursday conducted more raids in their hunt for the gunman that killed 39 people at an Istanbul nightclub, detaining several people at a housing complex in the city’s outskirts, the state-run news agency reported.

Anadolu Agency said gendarmerie police and special operations teams conducted raids in the Silivri district, detaining an undisclosed number of people from China’s Muslim Uighur community. The report said that those rounded up were suspected of “aiding and abetting” the gunman.

Deputy Prime Minister Veysi Kaynak told Turkish news channel A Haber on Thursday that investigators believe the suspect is likely a Uighur. Officials have said they know the man’s identity, but they have not made the name public.

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Kaynak said authorities were close to catching the gunman, telling A Haber that “the circle is closing in” on the suspect, who vanished after the attack.

Kaynak added that officials could not rule out the possibility that the gunman has made it out of the country, but he said it was still seen as more likely that search efforts would yield results inside Turkey.

At least 39 other people -- including 11 women -- are already in custody over suspected links to the attack on Istanbul’s upscale Reina nightclub during New Year’s celebrations.

The Islamic State of Iraq and Syria (ISIS) has claimed responsibility for the massacre, saying it was in reprisal for Turkish military operations in northern Syria. Most of the victims of the attack were foreigners from the Middle East.

Turkish media have widely published images of the suspect, including a selfie video filmed at Istanbul’s Taksim Square.

Prior to Kaynak’s remarks suggesting a Uighur was being sought, Sabah newspaper, which is close to the government, said the suspect is a Kyrgyz national born in 1988.

Security has been tightened around Istanbul and at border crossings and airports to prevent him from fleeing Turkey.

Deputy Prime Minister Numan Kurtulmus suggested in an interview with the Hurriyet Daily news newspaper and other sister publications that “foreign intelligence services” could be behind the attack, pointing at the “professional” manner in which it was carried out.

“I am of the opinion that it’s not possible for the perpetrator to have carried out such an attack without any support. It seems like a secret service thing. All these things are being assessed,” Hurriyet Daily News quoted Kurtulmus as saying in the interview published on Thursday.

Rumors have spread on Turkish social media in recent days -- fuelled by vague remarks from Turkish officials suggesting a U.S. role in the attack -- that the gunman was linked to the CIA.

The New York Times notes that, a day after the attack, Turkish lawmaker Sammil Tayyer declared on Twitter -- without providing any evidence for his assertion -- that the “attack is an act of CIA. Period.”

Turks’ collective distrust of the American government has grown as the long-standing ties between Washington and Ankara faltered during the last year. President Recep Tayyip Erdogan and his staff have suggested American backing for a failed coup aimed at toppling him earlier this year, and Turkish press widely pinned the assassination of a Russian diplomat in Turkey on a Turkish cleric who has lived in exile in Pennsylvania for years.