Turkish police have detained two Daesh-linked suspects after one man was killed in an attack on a Catholic church in Istanbul, Interior Minister Ali Yerlikaya said Sunday.

"Two murder suspects who caused the death of our citizen Tuncer Cihan during Sunday mass at Sarıyer Santa Maria Church have been caught," Yerlikaya told reporters.

"I congratulate our Istanbul police and heroic police officers who identified and caught the perpetrators. I once again express my condolences to the family and relatives of our citizen who lost his life.

"Both suspects are of foreign nationality. We assess that the suspects – one Tajikistani and the other Russian – are affiliated with the Daesh terror group," he added.

Throughout the day, Turkish security forces conducted raids on 30 addresses, resulting in the apprehension of 47 suspects so far, Yerlikaya said.

The number jumped to 51 in ensuing operations, authorities reported on Monday.

The shooting, condemned by Pope Francis and Turkish officials, was claimed by Daesh on its Telegram channels on Sunday.

The extremist group said that it "attacked a gathering of Christian unbelievers during their polytheistic ceremony" inside the church.

The statement claiming responsibility was published on Aamaq, the media arm of the militant group, along with photos of two masked men holding guns whom it identified as the attackers.

It described the attack as killing one person and wounding another, while Turkish authorities said no one was injured besides the person killed.

Two masked gunmen opened fire on worshippers Sunday at the church in Istanbul's Sarıyer district, killing one, Turkish officials said earlier.

Condemning the "heinous attack," Istanbul Governor Davut Gül told reporters that the victim of the attack was 52 years old.

Yerlikaya earlier said the incident took place at 11.40 a.m. local time (8:40 a.m. GMT), during morning mass, which around 40 people attended, including Poland's consul general in Istanbul, Witold Lesniak, and his family.

Turkish officials said it looked like a targeted attack against one person rather than against the Catholic church.

They also suggested that, but for a weapons malfunction, there might have been more casualties.

"After the second shot, the gun didn't work, then they (the attackers) ran," Sarıyer district's mayor Şükrü Genç told reporters.

"At this moment, everyone lay on the floor. There were around 35 to 40 people inside."

The Polish Foreign Ministry didn't comment on the diplomat's presence, saying only it was "monitoring the situation".

Television images showed police and an ambulance outside the ornate 19th-century church.

Security footage from before the attack showed a pair of men wearing black ski masks with their hands hidden in their pockets. One was wearing sunglasses.

Yerlikaya assured that police were working hard to solve the crime and said, "Those who try to disrupt the unity and solidarity of our nation will never succeed. I want to especially underline this."

‘Closeness to community’

President Recep Tayyip Erdoğan, who was in the central Anatolian province of Eskişehir for his party's rally ahead of the March local elections, expressed condolences during a phone call with the priest of the Italian church and other local officials.

The "necessary steps are being taken to catch the perpetrators as soon as possible," he said, according to his office.

Several other Turkish officials called the assault "despicable" and offered condolences to the victims’ families.

During a visit to the church, Ali Erbaş, the head of Türkiye's Presidency of Religious Affairs (Diyanet), said: "I would like to stress that differences are our richness. Places of worship, especially during worship, have complete inviolability. According to our belief, mosques, churches and synagogues are inviolable, regardless of which faith they are a place of worship for."

"As a state and a nation, we will always preserve our unity and solidarity. The coexistence of people of different beliefs is a very important richness for us," he added.

Condolences

Pope Francis expressed his support for the Catholic church after the attack, in comments at the end of his weekly Angelus prayer in St. Peter's Square at the Vatican.

Italy's Prime Minister Giorgia Meloni also decried the attack and said her government is following updates.

"We express deep condolences and the strongest condemnation of the despicable act," she added on X.

Fener Greek Orthodox Patriarch Bartholomew also expressed his condolences to the spiritual leader of the Latin Catholic community, Massimiliano Palinuro, over the attack.

Bartholomew, who is based in Istanbul, phoned Palinuro and conveyed his condolences to the family of the person who lost his life in the armed attack at the church and to the Catholic community.

Expressing his belief that the authorities will do what is necessary to shed light on the tragic incident, Bartholomew said social peace and the harmonious coexistence of religious communities is an indelible characteristic of Türkiye.

Widespread condemnation

The incident comes more than a week after Italian Prime Minister Giorgia Meloni met Erdoğan in Istanbul.

Türkiye's ruling Justice and Development Party (AK Party) spokesperson Ömer Çelik said the attackers took aim at a citizen during the mass.

"Our security forces are conducting a large-scale investigation into the matter," he said. "Those who threaten the peace and security of our citizens will never achieve their goals."

Istanbul Mayor Ekrem Imamoğlu said, "We will never allow those who aim at our unity and peace by attacking houses of religion in our city."

In December last year, Turkish security forces detained 32 suspects over alleged links with Daesh who were planning attacks on churches and synagogues, as well as the Iraqi Embassy.

Daesh extremists have not previously targeted places of worship on Turkish soil but they have carried out a string of attacks, including against a nightclub in Istanbul in 2017 that left 39 people dead and a 2015 bombing attack in Ankara that killed 109.

In its statement Sunday, Daesh said the attack had been carried out in response to the group leader's call to kill Jews and Christians everywhere.