Khaled Harah, a first responder, says a government helicopter dropped four barrel bombs last night on the neighbourhood of Zabadieh and that one of them released chlorine gas.
The report, which was posted online today, could not be independently verified and it was not clear how it was determined that chlorine gas was released.
The Britain-based Syrian Observatory for Human Rights, an activist group that tracks the civil war in Syria, also reported that government barrel bombs struck the neighbourhood.
The Observatory made no mention of chlorine gas.