The church is in an ancient Christian neighborhood that lies outside the Damascus old city's Bab Sharqi, and is in an area of many churches, chapels, and Christian cemeteries.
Some initial reports said it may have been a car bomb, but regional sources as well as the popular regional account
War Monitor indicate that
"A suicide bomber blew himself up with an explosive belt inside the Greek Orthodox Church of St. Elias in the Douileh area of Damascus, Syria."
And
Reuters notes that "It was the first suicide bombing in Damascus since Bashar al-Assad was toppled by an Islamist-led rebel insurgency in December." Reuters says at least 20 people were killed and dozens more injured, amid conflicting emergency response reports.