27 worshippers were killed and 63 injured in a suicide bomb attack during a mass service in the St. Mar Elias Church in Damascus on Sunday, Syrian state media SANA reported.

The Syrian Interior Ministry said that a gunman opened fire on worshippers before detonating an explosive vest, blaming the Islamic State (IS) for the attack.

Syrian special forces conducted operations against multiple IS militant cells on Monday, apprehending six individuals they claim are connected with the attack, according to SANA. 

However, no group immediately claimed responsibility.

A funeral service for nine of the slain worshippers was performed by the Greek Orthodox Patriarch of Antioch John X at the partially destroyed church.

Condemnation from within the Middle Eastern country has been widespread.

Syrian President Ahmad al-Sharaa expressed his deep condolences for the families of the victims of the attack, adding that he pledges to “apprehend all those who participated in and planned this heinous crime and bring them to justice to face their just punishment.”

Syria’s newly appointed Grand Mufti Osama al-Rifai echoed similar sentiment, writing in a Facebook post that “we denounce this unjustified act,” adding that “We reiterate our firm stance of rejecting violence, terrorism, and criminal acts, regardless of their motives and causes.”

The United States, European Union and foreign ministries of Middle Eastern nations such as Qatar, Saudi Arabia and Lebanon condemned the attack.

U.S. Special Envoy for Syria Tom Barrack wrote on X that the U.S. will continue to “support the Syrian government as it fights against those who are seeking to create instability and fear in their country and the broader region.”

Khalid Alsadek contributed to the reporting of this story