One person was killed during an attack on a church in Istanbul's Sarıyer district during a service on Sunday, Interior Minister Ali Yerlikaya said, adding that "large-scale investigation into the issue and efforts to catch the attackers have been initiated."

"Today around 11:40 a.m. during the service at the Santa Maria Church in Sarıyer's Büyükdere neighborhood, C.T. among those attending the ritual was attacked with a gun by two masked people and unfortunately lost their life," Yerlikaya said in a post on his official social media account on X, formerly Twitter.

"A large-scale investigation into the issue and efforts to catch the attackers have been initiated," he added.

"We strongly condemn this vile attack," the minister said.

Footage from the church showed a number of police cars and an ambulance dispatched outside the building.

Other officials, including Vice President Cevdet Yılmaz, Justice Minister Yılmaz Tunç and Justice and Development Party (AK Party) spokesperson Ömer Çelik, condemned the attack on the Italian church.

"We condemn in the strongest terms the armed attack on a person during the service at the Santa Maria Church in Sarıyer, Istanbul, and express our condolences to the family of the person who lost their life," Yılmaz said in a statement on his social media account.

"Our security forces are conducting a large-scale investigation to shed light on the incident and hold the perpetrators accountable to justice," he said.

The motive for the attack was also not immediately clear.

"Our security forces are conducting a large-scale investigation into the matter," Çelik said in a written statement on X.

"Those who threaten the peace and security of our citizens will never achieve their goals," he added.

Tunç meanwhile stated that a deputy chief prosecutor and two public prosecutors were assigned to shed light on the armed attack while strongly condemning the incident.

"An investigation has been launched by the Istanbul Chief Public Prosecutor's Office regarding the attack in which one person lost their life, and a deputy chief prosecutor and two public prosecutors have been assigned to shed light on the incident. Efforts are continuing to identify and capture the suspects who carried out the attack. The investigation is being carried out in a multifaceted and meticulous manner," Tunç said in a post on X.

Later in the afternoon, the Presidential Communications Director informed through social media channels that Erdoğan held talks with the priest of Santa Maria Italian Church, highlighting the necessary steps being undertaken to catch the perpetrators of the attack.

"Our President, Mr. Recep Tayyip Erdoğan, had a telephone conversation with Sarıyer District Governor Mr. Ömer Kalaylı, Priest of Santa Maria Italian Church Mr. Anton Bulai and Poland's Consul General in Istanbul Mr. Witold Lesniak, regarding the attack that took place at the Santa Maria Italian Church in Sarıyer, Istanbul," Altun said on X.

Poland has a large Catholic population, and it is possible that Poles living in Istanbul were among the worshippers at the church.

"Expressing his condolences and wishes to get well soon to the entire community, our president stated that the necessary steps are being taken to catch the perpetrators as soon as possible," he added.

Italy's Foreign Minister Antonio Tajani said his ministry was following the situation along with the Italian Embassy in Ankara and the consulate in Istanbul.

"I express my condolence and firm condemnation for the vile attack on Santa Maria Church,″ Tajani wrote on X. He added, "I am certain that the Turkish authorities will arrest those responsible."

Ali Erbaş, the head of Türkiye's Presidency of Religious Affairs (Diyanet), and Parliament Speaker Numan Kurtulmuş also condemned the attack.

Erbaş denounced the "heinous attack" and extended condolences to the victim's family.

Kurtulmuş called the assault "despicable" and also offered condolences to the victim's family.