Activists have told Reuters that three people have been killed in tank and sniper fire in the Damascus suburb of Harasta.
Rebels in a northern town close to the Turkish border also reported one of their fighters was shot dead by a sniper early on Friday and a Reuters journalist in the town heard what sounded like four rounds of tank fire.
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Two were taken to hospital and three others were treated at the scene.
Nikki Haley said the organisation was not worthy of its name.
Rain in the northwest with some heavy outbreaks will sink slowly southeastwards