According to state media, at least 13 Syrian military men were murdered in a roadside bomb strike as their bus crossed a bridge in central Damascus during rush hour on Wednesday.
Syrian state television uploaded photographs of the bus's burnt cabin on its Telegram channel, with rescue personnel spotted collecting human pieces. According to the broadcaster, at least 13 individuals were killed and three more were injured.
It stated two explosive devices detonated when the bus was on the Hafez al-Assad bridge, and a third device was defused by an army engineering unit in a "terrorist" blast, according to officials.
This year, alleged Islamic State militants who still operate in the huge desert territory of eastern Syria have launched several strikes on army vehicles.
According to the United Nations, at least 350,000 people have died in a civil war that began a decade ago.
Since loyalist forces loyal to President Bashar al-Assad took control of opposition areas around the city, blasts in Damascus have been infrequent. Assad now has control of the majority of the country, thanks to Russia's military involvement and Iran's Shi'ite militias.