A suicide bombing has struck near the Maryameye Orthodox Church in the Old City of Damascus, killing at least four people, the pro-government Ikhbariya TV channel reported.
The state-run station said the attack occured in the central neighbourhood of Bab Touma, a famous Christian quarter of the capital on Thursday.
It also reported several injuries, but has given no indication of numbers at this time.
The Maryameye church is near the cobblestone Roman "Straight Street" that runs past many old buildings and a luxury restaurant once frequented by President Bashar al-Assad and his inner circle.
Syria's minorities, especially Assad's Alawite sect, an offshoot of Shia Islam, have generally stood behind the president during the conflict in which the UK-based Syrian Observatory for Human Rights says more than 100,000 people have been killed.
Christians had tried to remain neutral, but increasingly their young men have been joining pro-Assad fighters.
The Old City is the historic heart of Damascus. Before the war, it drew crowds of tourists to its souks, monuments,
religious sites, restaurants and craft shops.
It was the first major blast reported inside the walls of the Old City, a UNESCO World Heritage site that is one of the oldest cities in Middle East, dating back about 4,000 years.
News outlets close to rebels fighting to topple Assad said the explosion was caused by a mortar bomb.
The Syrian Observatory, a pro-opposition monitoring group, said two mortar rounds had hit Amin Street, home to Shia Muslim families who generally back Assad.