Updated at 12 p.m. ET
Turkish authorities have made multiple arrests on Tuesday as they search for the gunman who attacked an Istanbul nightclub in the early hours of New Year's Day, killing at least 39 people.
A lone gunman shot his way into the Reina nightclub, which was packed with holiday revelers.
Police arrested two foreign nationals that they described as suspects at Istanbul's Ataturk Airport, according to the state-run Anadolu news agency. They then searched the pair and took them to the capital's police headquarters.
"The country remains on high alert, especially at transport hubs and border crossings," as NPR's Peter Kenyon in Istanbul reports.
This follows earlier media reports Tuesday, which were later reversed, that police had identified and named the suspected lone gunman at the Reina nightclub.
The state-funded TRT World news network showed images of a passport from Kyrgyzstan belonging to the apparent suspect and named that person, as Peter reports, but the broadcaster stopped showing the passport page shortly after without explanation. We have since removed that name as well from our story.
Police denied that the passport was linked to the shooting, as Peter reports.
"The Hurriyet newspaper says police detained a woman in the town of Konya who's described as the wife of the main suspect in the attack," as Peter reports. "According to the paper, she told police her husband never showed any sympathy for ISIS, which has claimed responsibility for the attack."
Turkish authorities have released a "selfie" video of the apparent gunman. The video shows the man walking along a city street. Turkish authorities did not say when the video was recorded or how they obtained it.
Peter further reports:
"The claim of responsibility by ISIS prompted Turkey's deputy prime minister Numan Kurtulmus to say Turkey's response will be to step is military attacks against ISIS in northern Syria.
"That escalation appears to have already begun. The military tells the state-run Anatolia News Agency that Turkish attacks have killed at least 18 ISIS fighters in the past 24 hours and at least 150 ISIS targets have been hit by air strikes or tank and artillery fire in recent days."
Police raids continue in Istanbul neighborhoods, Peter reports, and 14 people are being held for questioning in connection with the attack in addition to the pair from the airport.