Istanbul, Turkey - One man died after armed assailants opened fire in an Italian church in Istanbul, Turkey, during Sunday mass in an apparent assassination attempt that was swiftly condemned by Pope Francis.

The attack occurred at around 11:40 AM at the Santa Maria church in the Sariyer district of Istanbul on the European side and was carried out by two masked men, Interior Minister Ali Yerlikaya said on social media.

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

The minister said an individual identified only as C.T. – who was among those attending Sunday's service – was the target of the gun attack and lost his life.

An investigation had been launched to find the attackers, Yerlikaya added, who fled the scene after the shooting.

Local officials said around 40 people attended the mass.

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

"We strongly condemn this vile attack," Yerlikaya said.

Security footage ahead of the attack showed a pair of men wearing black snow masks with their hands in their pockets, and one was seen wearing black sunglasses.

Francis expressed his support for the church after the attack.

"I express my closeness to the community of the Santa Maria" church in Istanbul, the Argentinian pope said at the end of his weekly Angelus prayer in St. Peter's Square at the Vatican.

Italy's Foreign Minister Antonio Tajani also expressed his "condolences and firm condemnation" over the attack, and backed the Turkish authorities to find the killers.

The incident comes more than a week after Italian Prime Minister Giorgia Meloni met with Turkish President Recep Tayyip Erdogan in Istanbul.

Turkey's ruling AKP party spokesperson Omer Celik 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 governor Davut Gul told reporters at the scene that there were no injuries.

The motive for the attack was also not immediately clear.