(CP) The Islamic State claimed a Sunday terrorist attack against a Roman Catholic church in Istanbul, Turkey, that killed a mentally disabled Muslim man.

The terrorist organization admitted through its media arm to attacking "a gathering of Christian unbelievers during their polytheistic ceremony" at the Santa Maria Church in Istanbul's Buyukdere neighbourhood, according to The Associated Press.

Footage obtained by Reuters shows the moment masked gunmen opened fire during the church's Sunday Mass.

Police arrested two men early on Monday, one of whom is Russian and the other from Tajikistan, according to Turkey's Interior Minister Ali Yerlikaya. The arrests followed police raids at more than 30 locations, during which 51 suspects were detained, AP reported.

"Both of the suspects are foreign nationals," Yerlikaya said. "One of them is from Tajikistan and the other is Russian, and we evaluated them to be with the Islamic State."

Yerlikaya also said Sunday in a post on X that he and the Turkish government "strongly condemn this vile attack."

Tuncer Cihan, 52, who was shot and killed during the attack, was "a person who had done nothing wrong," according to the church's lawyer, Avsin Hatipoglu, who spoke to the AP. He said the church is reportedly requesting increased security in the vicinity.

The lawyer added that Cihan was not even a Christian but Alevi, a sect of Shia Islam. Cihan's nephew identified him and noted that he was mentally disabled, according to The New York Post. Yerlikaya also confirmed the identity of the victim.

Sukru Genc, the mayor of Sariyer District, told a local news outlet that Cihan was standing near the entrance to the church when the attack took place, according to CNN.

"According to the priest, he was constantly going to church, and the priest knew this person and referred to him as 'a good person,'" Genc said.

"Such provocations will never be allowed in our country," Akif Cagatay Kilic, one of Turkish President Recep Tayyip Erdogan's top political advisers, wrote in a statement posted to X on Sunday. "The perpetrators will be caught as soon as possible and held accountable before justice."

Bishop Massimiliano Palinuro, who serves as the apostolic vicar of Istanbul, told EWTN News that Cihan was murdered "during the consecration while all the congregation was praying."

"We are worried about the future because if this is a sign of the religious intolerance, for our community, it could be a bad sign. Let us pray," Palinuro said.

In response to news of the arrests, Palinuro said, "We trust in the justice of God."

The Turkish bishops' conference condemned the attack in a Sunday statement, urging people to pray and to avoid "[spreading] the culture of hatred and religious discrimination," according to Catholic News Agency.

"We firmly condemn this act of violence against humanity," the statement said, which was signed by Archbishop Martin Kmetec of Izmir.

"We trust that the Turkish state security forces will find those responsible and that justice will be done," he said. "We firmly demand that the truth be revealed and that greater security be guaranteed to our communities and churches."

Pope Francis wrote on X: "I express my closeness to the community of the Church of St. Mary Draperis in Istanbul, which suffered an armed attack during Mass that killed one person and injured several others."

Approximately 25,000 Roman Catholics live in Turkey as of 2022, according to the U.S. State Department.

Yerlikaya claimed Turkey has detained 2,086 people with suspected ties to the Islamic State and arrested 529 since last June, according to Reuters.

Twenty-five people suspected of having ties to the Islamic State were arrested in Turkey on Jan. 3 amid allegations that they were planning to attack churches and synagogues, according to the Turkish news outlet Anadolu Agency.

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