Twelve civilians and policemen were killed and tens others wounded by the gunshot of "armed terrorist" groups that "took advantage of peaceful demonstrations" in some Syrian cities, Syrian Arab News Agency (SANA) reported.
It said 35 policemen were wounded, including five officers, Xinhua reported.
The agency said eight people were killed in al-Qabon area near Damascus, adding that armed groups were terrorizing people and forced them to demonstrate.
In Barzeh, one of Damascus' neighborhoods, a policeman was killed, and a civilian was killed in Douma, a Damascus suburb. Two policemen were also killed, one in Homs province in central Syria and the other in Idleb in the north.
SANA said terrorism groups cut off roads with trash containers and tires and erected roadblocks.
Syria has been gripped by four months of protests demanding sweeping reforms and broader freedom and democracy. The Syrian government has blamed violent acts on armed groups and foreign conspiracy.