About 30 people died in sectarian violence in Syria over the weekend after the mutilated bodies of three regime supporters were found in the central Syrian city of Homs, activists said.
The killings were a serious escalation in the bloodshed stemming from a four-month-old uprising against President Bashar Assad's authoritarian regime.
There have been fears that the revolt would enflame tensions between Syria's potentially explosive mix of religions and minority groups.
Most Syrians are Sunni Muslim, but Assad and the ruling elite belong to the minority Alawite sect, an offshoot of Shiite Islam.
The London-based Syrian Observatory for Human Rights and a Syrian activist in Homs put the death toll at 30 and said they have the names of the victims.
But another activist in Homs said he was not certain if the death toll was as high as 30. He suggested the real number may be about half.
The director of the Syrian Observatory for Human Rights, Rami Abdul-Rahman, said the killings were a "dangerous transformation".
The violence was reminiscent of the kind of sectarian battles that have troubled Syria's neighbours Iraq and in Lebanon.
The bloodshed began after three Alawites were found dead in Homs on Saturday, a resident said. The next day, six more bodies from various sects were found dumped in the city.
A resident said the killings of Alawite members sparked a "violent reaction" from pro-government thugs called shabiha, who went on a rampage, opening fire indiscriminately in predominantly Sunni neighbourhoods in Homs, and setting fire and breaking into their shops.
"It was a catastrophe, the situation could easily have slipped out of control," he said, adding things are calmer today but tensions remain high.
The dead included a 27-year-old mother-of-three, who was shot as she left her home, and a man in his 50s who was struck by a bullet while on his balcony.