"A suicide bomber wearing a belt of explosives blew himself up in al-Jisr al-Abayad [in] Damascus, claiming four lives, including a woman," the state news agency said. SANA published pictures of the blast site showing bloodstains on the road, smashed roof tiles and a pink woman's shoe.
Seventeen people were wounded, Iran's semi-official Press TV reported.
A government building in the capital appeared to have been the target, the Syrian Observatory for Human Rights said.
Damascus has been the site of numerous bombings since the civil war erupted in March 2011. Last week, at least 15 people were killed and more than 30 injured in a suicide bombing near a bus station in Damascus, the BBC said.