The Observatory, meanwhile, said that five civilians, including two women and three men, were gunned down in the Damascus' countryside of Tishreen, adding that pro-government gunmen were behind the killing.
Activists also reported heavy shelling on rebel strongholds in eastern and southern rims of Damascus and elsewhere in the war-engulfed country on Thursday, putting the death toll on Thursday at 116.
Still, the account could not be independently confirmed.
As the violence keeps grinding on, Syria's Minister of Endowment Mohammed Abdel Sattar called for "million-man prayers" to be held on Friday for the peace of Syria and on the occasion of the birthday of Islam Prophet Mohammad.
The prayers will be held at Syria's mosques nationwide on Friday to appeal for the re-establishment of security in the country, which has been gripped by a prolonged crisis that has killed more than 60,000 people, according to a recent UN tally.
Earlier in the day, President al-Assad attended special prayers at a Damascus mosque to mark the prophet's birthday.
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