The terrorist attack was on Sunday at a church in Damascus.
The attacker began shooting at people and then blew himself up inside the church.
The latest reports show at least 20 dead and at least 50 wounded, with the numbers still climbing.
News reports say the attacker was affiliated with the jihadist group Islamic State.
At approximately the same time, attacks took place on other churches across Syria.
A suicide bomber also targeted a Monastery in Damascus.
Yet a third terrorist team attacked a church in Maqsura, placing explosive devices at the door.
In the cities of Homs and Hama, several churches were also attacked by shooters.
Leaflets were also posted on the doors of these churches, reading, “Your turn is coming.”
These were the first terrorist attacks on churches in Damascus and across Syria since Bashar al-Assad was overthrown by rebel forces in December.
Interim President Ahmed al-Sharaa — whose Sunni Islamist group, Hayat Tahrir al-Sham (HTS), is a former al-Qaeda affiliate in Syria — has repeatedly promised to protect religious and ethnic minorities, however, the country has been rocked by two waves of deadly sectarian violence in recent months.