At least 15 people were killed and more than 50 wounded Monday when mortar shells hit pro-regime areas in Syria's northern province of Idlib, dpa quoted the Syrian Observatory for Human Rights monitoring group as saying.
The mortar shells hit Idlib after armed group vowed to retaliate against the regime's air strikes on Idlib last week, which killed at least 30 and wounded others.
Syrian television confirmed that all casualties in Monday's attack on residential areas and a market were civilians, including children.