By Halit Suleyman

DAMASCUS, Syria

At least 17 civilians including women and children were killed Saturday in a Syrian regime airstrike east of the capital Damascus, according to a pro-opposition civil defense official.

The source, who wished to remain anonymous due to security concerns, said the attack, which targeted the city of Hamouriyah in the Rif Dimashq province, had also injured 50 others.

Rescue efforts are ongoing to find the civilians trapped under the debris, the source added.

Syria has been locked in a vicious civil war since early 2011, when the Bashar al-Assad regime cracked down on pro-democracy protests -- which erupted as part of the "Arab Spring" uprisings -- with unexpected ferocity.

Since then, more than a quarter of a million Syrians have been killed and more than 10 million displaced, according to UN estimates.