BEIRUT — At least 15 were killed and more than 30 were wounded in a suicide bomb attack at a bus station in a suburb west of Damascus, state media said on Tuesday.

State television said all fatalities were civilians but the Syrian Observatory for Human Rights, a British-based, anti-Assad monitoring group, said six of the dead were soldiers and that two children were also killed at the bus stop in Soumariya, a major hub for transport in and out of the capital.

"The number is likely to rise because there are about 25 wounded, some of them in critical condition," the Observatory said in an email.

Suicide attacks are a common tactic by insurgents fighting to overthrow President Bashar Assad, whose family has ruled Syria for more forty years.

More than 100,000 people have been killed in a civil war which started with peaceful pro-democracy protests in March 2011 that were suppressed with force.