Activists say that a bomb has struck a security vehicle in the Syrian capital of Damascus, causing casualties. The Britain-based Syrian Observatory for Human Rights and the Local Coordination Committees say Sunday's blast occurred in the upscale neighborhood of Mazzeh. The LCC said the blast occurred near a military airport in the neighborhood. The Observatory said the explosion caused casualties but did not give a breakdown. A video posted online by activists showed thick black smoke billowing from what it said was Mazzeh, according to a report of the Associated Press.