Police identified the suspect as Abdulgadir Masharipov, who is believed to be responsible for killing 39 people at Reina nightclub in Istanbul.
Suspected Reina nightclub gunman Abdulgadir Masharipov, who shot dead 39 people on New Year's Day, was arrested by Turkish security forces late Monday night.
Turkish media has reported that the suspect was nabbed in an apartment in Istanbul's Esenyurt district with his four-year-old son, another Daesh terrorist and three women from Egypt, Somalia and Senegal.
Police also found two pistols, mobile phone SIM cards, and $197,000 in cash at the apartment.
Istanbul Governor Vasip Sahin said the suspect received training in Afghanistan and was a "well-trained terrorist."
Sahin also added that Masharipov entered Turkey illegally in January 2016 and thanked the Turkish security forces who had gone through 7,200 hours of CCTV footage to capture the suspect.
For more on the suspect, TRT World's Soraya Lennie is at the apartment where he was captured.
The suspect, who appeared to have repeatedly changed addresses before and after the attack, is being questioned at Istanbul police headquarters.
About 50 people have been detained in raids on 152 addresses since the shooting.
TRT World's Zeina Awad is at the police station in Istanbul, where the suspect is being held.
Turkish President Recep Tayyip Erdogan responded to the arrest of the suspect, saying it shows the justice system at work.
"Nobody in this country can get away with their crimes. Anyone who committed a crime will be held accountable within the rule of law. The arrest of the perpetrator of the Ortakoy massacre is another example of that. I would like to congratulate our security forces and those others who has participated in this very successful operation," Erdogan added.
Turkish Deputy Prime Minister Numan Kurtulmus, who is also the government spokesman, commented on the arrest saying, "Our war with terror and the powers behind it will continue to the end."
Kurtulmus, during an interview with Turkish broadcaster, A Haber, also said, "It appears the Reina attack is not just a terrorist organisation's act, but there was also an intelligence organisation involved. It was an extremely planned and organised act."
TRT World's Francis Collings brings us the last minute updates from Istanbul.