"Syrian security forces have been firing for the last two hours in the neighborhood of Ras Al-Nabee where there is the Al-Rahman Mosque," a focal point of demonstrations, a witness said by telephone.

At least three were killed and dozens wounded, the witnesses said, referring to the violence as "a real massacre with snipers shooting to kill."

The gunfire, according to both witnesses, came from the neighborhood of Al-Quz.

Another witness, a rights activist, said the shots were aimed at the mosque and left "four dead and 15 wounded."

Five people had earlier been wounded in a drive-by shooting reportedly carried out by plainclothes government agents in the Mediterranean town, according to a witness. Seven cars "carrying people sent by the regime arrived in front of the Abu Bakr Al-Siddiq Mosque and their occupants opened fire" during noon prayers, the witness said.

The perpetrators quickly took flight, although witnesses were able to record the license plates of some of their vehicles. "The people behind this shooting are regime thugs and their names are known to us," the witness said.

The official SANA news agency quoted a government source as saying an "armed group" had ambushed an army patrol in the city, killing one soldier and wounding others. The source said the incident took place on the Latakia-Tartous Road where the "armed group" was "hiding to the east of the road between the trees and buildings."

Army tanks and soldiers circled the city, preventing people from entering. Telephone lines, Internet access and electricity were cut in the area.

Protests erupted in Syria more than three weeks ago and have been growing steadily every week, with tens of thousands of people calling for sweeping reforms in President Bashar Assad's regime. More than 170 people have been killed.

Assad said Sunday that the country is "moving ahead on the road of comprehensive reforms," SANA said. In recent weeks, Assad has answered the protesters with both force and limited concessions that have failed to appease an emboldened movement inspired by the Arab uprisings in Tunisia and Egypt.