Posted 5/1/2012 7:35:34 AM UTC
Updated 5/1/2012 1:37:19 PM UTC
Nine of the victims, of two were children, were all members of the same family.
The mortar attack wounded many others.
On Monday, nine people were killed in the attacks in Idlib and capital Damascus, and more than 100 were wounded.
Separately six other people were killed in the clashes across the country, last week.
The attack marks another violation of a shaky UN-brokered truce, which has already been marred by sporadic clashes and a string of explosions in the capital, Damascus, last week and central Idlib on Monday.
UN Secretary General Ban Ki-Moon condemned the attacks and expressed his worries over the ongoing violence.