Police searched two houses and arrested five people during the operation to detain the suspect behind the Istanbul nightclub attack, ITV News understands.
It is believed three women and two men have been detained.
According to police sources, the man entered Turkey from Iran, but since the attack in the early hours of New Year's Day has never left Istanbul.
The suspect was pictured wearing a bloodied grey t-shirt and was taken to a city hospital under a large police escort on Monday evening.
Some police sources suggest he has changed location up to four times.
The suspected gunman behind the Istanbul nightclub attack was found at a house belonging to a Kyrgyz friend in a special police operation in Istanbul's Esenyurt district, according to private NTV television.
Hurriyet newspaper and other media identified the suspect as Abdulkadir Masharipov, an Uzbek national.
ITV News understands he is currently being treated in hospital for unknown injuries.
Media reports said he would 'undergo medical checks' before being taken to a police headquarters for questioning.
Dogan news agency published an image showing a bruised, black-haired man in a grey, bloodied shirt being held by his neck. NTV television said he had resisted arrest.
The suspected gunman had been on the run since the attack.
The suspected gunman who killed 39 people in an Istanbul nightclub on New Year's Day has been caught in the city's Esenyurt district, according to various Turkish media.
Islamic State claimed responsibility for the attack, which it said was revenge for Turkish military involvement in Syria.
Soon after the attack, Turkish authorities identified the main suspect who they said was a member of the Uighur community - a Muslim group who lived in western China.
A settlement is "in reach" to end the partition of Cyprus after more than four decades of division, Boris Johnson has said.Read the full story ›
- Video report by ITV News Middle East Correspondent Geraint Vincent
Mobile phone footage and CCTV captured the moment a gunfight erupted outside a court in Izra, one of Turkey's biggest cities, before a car bomb is detonated killing two people.
By stopping the car, Turkish police think they foiled a bigger attack which they say was plotted by Kurdish PKK militants.
The attack comes just days after Islamic State claimed responsibility for a New Year nightclub attack in Istanbul, that killed 39 people.
It has different causes and different aims but terrorism is casting a shadow over Turkey and putting security services under pressure as never before.
Turkey's Deputy Prime Minister, Veysi Kaynak said a much larger attack was apparently being planned based on the weapons found at the scene of the Izmir car bomb attack.
"Based on the preparation, the weapons, bombs and ammunition seized, it is understood that a big atrocity was being planned," Kaynak told reporters.
The attackers were reportedly carrying two automatic rifles, rocket launchers and eight hand grenades.
He said the attack, thought to have been carried out by Kurdish militants, would not stop Turkey's military involvement in Syria and Iraq.
Kurdish PKK militants were behind a car bombing outside a courthouse that killed two people in the Turkish city of Izmir, a governor said.
Provincial governor Erol Ayyildiz said a "clash erupted" after officers stopped a vehicle at a police checkpoint in front of Bayrakli courthouse.
"In this clash, terrorists detonated the car bomb while trying to escape," he told reporters.
A police officer and a courthouse employee were killed in the attack, he added.
Police shot dead two of the attackers who were armed with Kalashnikov rifles and grenades.
One policeman and a courthouse employee have reportedly been killed in a car bomb explosion in Izmir.
Izmir's Governor said the car stopped in front of the courthouse before the suspected attackers began a gunfight with police officers using kalashnikov rifles and grenades.
Some of the wounded are believed to be in critical condition.
Two attackers stormed their way into an Izmir courthouse after causing an explosion outside, ITV News understands.
The explosion was caused by a car bomb, the secretary general of the city municipality Bugra Gokce told reporters.
After the explosion - outside Gate C - the suspected attackers entered the building.
Both suspects were killed after being shot by police officers.
Footage recorded inside the courthouse shows dozens of armed security officials walking down the corridors with staff waiting patiently nearby.
Police in Turkey have shot dead a second suspected attacker in the western Aegean city of Izmir.
According to the Anadolu news agency, authorities are now searching for a third assailant.
Ten people are reportedly wounded after an explosion outside the city's courthouse earlier on Thursday.