At least 20 Christians were killed and 52 others were wounded on Sunday when a radical Islamic terrorist opened fire in an Orthodox church in Damascus, Syria, and then detonated an explosive vest, according to Syria’s interior ministry.

The terrorist, affiliated with ISIS, targeted Mar Elias Church in Dweila, on the outskirts of Damascus, the BBC reported. A person who witnessed the attack told AFP news agency that “someone entered carrying a weapon” and began firing at worshipers. A group of church members charged the attacker and “tried to stop him before he blew himself up,” the witness added.

Graphic footage of the aftermath of the bombing captured by the Syrian Civil Defence showed bloody bodies on the ground and rows of pews blown to pieces. Some local media reports said that children were among those killed in the terrorist attack, according to CBS News.

Issam Nasr, a man who was at the church during the attack, said that he saw people “blown to bits.”

“We have never held a knife in our lives. All we ever carried were our prayers,” Nasr said.

The bombing marks the first successful jihadist attack on a Christian church in Syria since Bashar al-Assad and his government were toppled by Islamic extremists in December, according to Reuters. The Islamic State was behind multiple other recent attacks on Christian churches in the country, but none were successful.

Interim Syrian President Ahmed al-Sharaa, who is part of a Sunni Islamist group that has ties to al-Qaeda, has repeatedly vowed to protect religious minorities in the country, but violence against Christians continues. There are over 500,000 Christians in Syria, and they are regularly the victims of government oppression and Islamic extremism, according to Open Doors, which ranks the country at 18th on the list of countries where Christians face the most persecution.