ROUGH CUT - NO REPORTER NARRATION<br/> <br />Two bombs detonated on a central Damascus highway, destroying nine cars, residents said.<br/> <br />It was a further sign that rebels fighting to topple President Bashar al-Assad are shifting tactics towards homemade explosives.<br/> <br />There were no immediate reports of casualties from the blasts from bombs planted under cars on al-Thawra Street, the latest blow to last month's crumbling U.N.-backed truce.
