Protesters set fire to offices of the ruling party in southern and western Syria on Saturday, burning tires and attacking cars and shops in the city on the Mediterranean coast, according to accounts by government officials, activists and witnesses.
Officials said at least two people were killed.
Demonstrators attacked a police station and offices of the Baath party in the town of Tafas, 10 kilometres north of Daraa, presidential adviser Bouthaina Shaaban told reporters.
In the coastal city of Latakia, dozens of people protested before attacking the Baath offices, said Ammar Qurabi, an exile in Egypt who heads Syria's National Organization for Human Rights.
A Syrian activist in touch with protesters in Latakia said hundreds had been demonstrating there since Friday evening, burning tires and shouting "Freedom!" A few protesters were attacking cars and shops, the activist said.
More than a week of protests centred in Daraa exploded into nationwide unrest Friday when tens of thousands of protesters marched in cities, town and villages around the country, posing the greatest threat in decades to the Baath party's iron-fisted rule.
Troops and soldiers opened fire in at least six places, killing some 15 protesters, according to witnesses, activists and footage posted on social networking sites.
A resident of Latakia who spoke to The Associated Press reported hearing gunfire Saturday evening, but could not say where it was coming from.
Shaaban said that an "armed group" had occupied the roofs of some buildings in Latakia, and claimed the group was shooting randomly at citizens.
A Syrian official told The Associated Press that two passersby were killed and two others wounded in Latakia by sniper fire from rooftops. He denied that the army had opened fire on protesters.
A hospital official in Latakia also said there were two dead and two wounded. He declined to give any other details.
Footage on a Facebook site run by Syrian activists showed what it said were the dead and wounded in Latakia. Young men carried one man by his limbs through a street, then another. They laid the second man limp in the street.
"It's the military police!" one shouted.
Footage from an opposition Syrian news agency uploaded onto YouTube claimed to show another man killed in Latakia
Qurabi said four people had been killed when armed forces fired on protesters Friday in Latakia, which is almost evenly divided between the country's majority Sunni Muslims and Alawites, members of a branch of Shia Islam who hold most positions of power, including the presidency.
Sit-in held in mosque
Activists called online for a popular peaceful uprising Saturday in all Syrian provinces, urging people to take part in funerals "and not return home."
By early afternoon, President Bashar Assad had pulled back police and soldiers from Daraa and released hundreds of political prisoners in an attempt to appease demonstrators furious about the violent government crackdown on dissent.
A Daraa resident said more than 1,000 people were holding a silent sit-in at the al-Omari mosque.
Protesters used the mosque as a refuge and ad hoc medical centre until they were driven out in a government assault on Wednesday. They retook the mosque during clashes with government forces on Friday, witnesses said.