Suicide bomber kills at least eight in Damascus: monitor
"At least four of them were soldiers, including a colonel," Observatory director Rami Abdel Rahman said.State news agency SANA said at least seven people were killed when a "suicide terrorist" detonated an explosive belt close to a sports club there.
Part of Kafr Sousa is a restricted zone that is home to ministers, senior security officials and intelligence headquarters, but the explosion took place elsewhere in the district.
Footage from the scene of the attack broadcast on state television showed what appeared to be blast marks and blood splattered across a wall next to the wreckage of a car.
Such attacks are rare in Damascus, a stronghold of the regime of President Bashar al-Assad which has been fighting rebels in Syria for nearly six years.
The Syrian capital is sometimes the target of shelling by the opposition forces who hold areas on the outskirts.
On December 16 a seven-year-old girl wearing an explosive belt blew herself up outside a police station in Midan district, wounding three police officers.
Two blasts near state security agencies in Kafr Sousa in December 2011 killed more than 40 people and wounded more than 150, the Syrian government said at the time.