Media reports say two masked gunmen attacked a Catholic church in Istanbul, turning morning mass into a scene of terror and killing one man.

The shooting reportedly happened at the Church of Santa Maria during Sunday mass at around 11:40 local time.

Turkey's Interior Minister Ali Yerlikaya said later on X, formerly Twitter that two gunmen who shot one person dead on Sunday during a service at a church in Istanbul and who are believed to be tied to Islamic State (IS) terror group.

BBC’s Russian Service cited Yerlikaya as saying that both suspects are citizens of other nations; one of them is reportedly from Tajikistan and another one is Russian. 

Shortly before, before, the IS terror group had reportedly claimed responsibility for the attack in a statement on Telegram, saying it was in response to a call by the group's leaders to target Jews and Christians.

Reuters reports that CCTV footage from inside of the church showed the masked gunmen entering the building and shooting the man who was walking in front of them.  The CCTV footage reportedly shows the men leaving almost immediately afterwards.

France 24 reports that local officials said around 40 people attended the mass, and suggested that there could have been more casualties. "After the second shot, the gun didn't walk, then they (the attackers) ran. At this moment, everyone lay on the floor.  There were around 35 to 40 people inside," Sariyer district's mayor Sukru Genc told reporters.

The Turkish president’s office says President Recep Tayyip Erdogan called the church's priest to offer his condolences and support, his office said, publishing a video of the call.

Pope Francis reportedly conveyed his condolences over the attack after his weekly Angelus prayer.

"I express my closeness to the community of Saint Mary Draperis Church in Istanbul that suffered an armed attack during mass that caused one death," Pope Francis said, according to the BBC.

Italian Prime Minister Georgia Meloni said on X that Italy's foreign ministry was following updates on the "despicable act" and condemned it.

The BBC notes that attacks like this on Turkiye's Christian minority are rare.  The local mayor said Muslims and Christians lived in harmony in the area, and that there was a real sense of shock among the community.