A suicide bomber blew up a vehicle at a bus stop west of Damascus on Tuesday, killing at least 15 people, state television said.
"The terrorist explosion in front of the bus stop in Somariyeh was caused by a suicide attacker," the broadcaster said in a news flash.
"It killed at least 15 citizens and wounded more than 30."
The bombing came as rebels, including al-Qaeda loyalists, pressed a four-day-old offensive to lift a year-long siege by the army of their positions in eastern suburbs of the capital.
Fighting also raged in the Qalamoun mountains north of Damascus, a border area where the army has been battling to cut rebel supply lines to neighboring Lebanon.
Health Minister Saad al-Nayef accused the rebels of killing "five doctors, five nurses and two ambulance drivers" in the Qalamoun town of Deir Attiyeh after they seized it from the army last week.