Turkey has identified the gunman in the Istanbul nightclub massacre, the foreign minister said Wednesday, as the president vowed that the country won’t surrender to terrorists or become divided.

The gunman, who killed 39 people during New Year’s celebrations at the Reina club, is still at large.

But Foreign Minister Mevlut Cavusoglu said authorities had identified the man, without providing details.

“The identity of the person who carried out the attack on the Reina nightclub has been established,” Cavusoglu told Anadolu in a live televised interview.

Turkish police, meanwhile, detained 20 suspected Islamic State group militants, including 11 women, believed to be linked to the attack, the state-run news agency reported. The operation was launched in the Aegean port city of Izmir.

Anadolu said the suspects were from the largely Muslim Russian republic of Dagestan, from China’s Muslim Uighur minority and from Syria.

It said they are thought to have lived with the nightclub attacker.

IS has claimed responsibility for the attack, which also wounded nearly 70 people.

Of those killed 27 were foreigners, many from the Middle East.

Islamic State said a “soldier of the caliphate” had carried out the mass shooting to avenge Turkish military operations against IS in northern Syria.

Floral tributes and Turkish flags, along with photos of victims, lie outside the Reina club after the New Year’s Day attack. Photo: AP/Emrah Gurel

The private Dogan news agency said that Wednesday’s police operation targeted three families who had arrived in Izmir about 20 days ago from Konya – a city in central Turkey where the gunman is thought to have been based before carrying out the nightclub attack.

At least 16 people were previously detained in connection with the attack, including two foreigners stopped Tuesday at the international terminal of Istanbul’s Ataturk Airport after police checked their cellphones and luggage.

President Recep Tayyip Erdogan said that the attack aimed to set Turks against each other and deepen fault lines, but that the country would not fall “for this game.”

Erdogan made the comments in a live speech from Ankara, the first time he has publicly addressed the nation since the attack.

All flags at half-mast in solidarity with #Turkey after the Istanbul terror attack. #Reina pic.twitter.com/Y8ygCiUNzE

— NATO (@NATO) January 3, 2017

Responding to accusations in the past that Turkey had given support to the Islamic State group, Erdogan said that “to present the country – which is leading the greatest struggle against Daesh – as one that is supporting terrorism is what the terror organisation wants.”

“In Turkey, no one’s way of life is under any threat. Those who claim this have to prove it. It is my duty to protect everyone’s rights.”

Police in Istanbul have set up checkpoints and are checking vehicles across the city as security levels remained high.

Police were stopping cars and Istanbul’s ubiquitous yellow taxis, with passengers and drivers holding up their identifications while officers inspected inside the vehicles.

Istanbul has been on high alert since the attack.

Hurriyet newspaper said the gunman had previously entered Turkey twice, in 2014 and in 2015.

He is believed to have slipped into Syria illegally, where he received training in the use of guns and bombs, and fought.

Turkish media reports claimed Tuesday that the gunman’s wife was in custody and had told police she didn’t know her husband was linked to IS as an eerie selfie video emerged of the alleged gunman on Tuesday, showing him silently touring Istanbul’s most famous square.