The killings occurred Wednesday in the Druze village of Qalb Lawzeh in the Jabal al-Summaq region, where Nusra Front fighters have dug up historic graves and destroyed shrines in recent months.
The Britain-based Syrian Observatory for Human Rights said the shooting occurred after the Nusra Front tried to confiscate the home of a Druze government official in the village. It said fighters shot one villager dead, prompting another villager to grab one of the fighters` rifles and kill a member of the jihadi group.
The Observatory said the jihadis later brought reinforcements and opened fire, killing 20 residents.
The main Western-backed Syrian National Coalition said "dozens of Druze young men" were killed in the shooting. It said an armed clash broke out "following an aggression by Nusra Front members."
Syrian state news agency SANA said a "horrible massacre" killed 30 people, including five members of the same family in Qalb Lawzeh. SANA added that jihadis torched several homes.
The Druze, a 10th century offshoot of Shiite Islam, made up about 5 percent of Syria`s prewar population of 23 million people. Lebanon and Israel also have large Druze communities.
The head of the Druze community in Lebanon, Sheikh Naim Hassan, condemned the killings and said efforts are being made to "contain this regrettable and painful incident." He called on all rebel and militant factions in Syria to avoid strife.
Asaad Kanjo, an activist from Idlib province who is currently in Turkey, said via Skype that very few details are emerging, adding that the Nusra Front is preventing people from passing a checkpoint about 3 kilometers (2 miles) from the village.
Activists estimate that several hundred Druze have been forced to convert to Sunni Islam since the Nusra Front seized the area last year.
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