Two Syrian rights groups said shelling of the town of al-Mitras began at dawn, killing six people.
The town lies near two other Sunni Muslim towns of Bayda and Banias.
Rights groups charge that regime supporters killed at least 248 people in those two communities in May. They said regime forces shelled Bayda before militias entered and carried out the alleged massacre.
"We are worried, because this is an isolated area and crimes can be covered up quickly," said Rami Abdul-Rahman of the Britain-based Syrian Observatory for Human Rights, which follows a network of activists in the field.
Syria's civil war has cleaved along the country's sectarian patchwork. Sunnis dominate the revolt, while Christians and other Muslim sects have mostly stood behind the regime.
Another Syrian activist who goes by the name of Abu al-Waleed said there were negotiations underway to hand over rebel fighters in exchange for regime forces promising not to allow harm to come to civilians.
"The fear is that they are trying to clean this area of rebel supporters - that is, the Sunni community," he said in a Skype call.
Also in Syria, the government raised the price of gasoline and transportation in its latest wartime austerity move, a step likely to increase hardship for many Syrians already suffering from the economic consequences of civil war.
The price of a liter (quarter gallon) of gasoline increased by 25 per cent, from 80 Syrian pounds (45 cents, on the black market) to 100 (57 cents), according to a government declaration.
Official Imad al-Assil said the decision would simultaneously raise transportation fees by 17 per cent.