At the moment, about the reasons for the chlorine leak in the reservoir is not reported
In particular, it is indicated that 362 people were hospitalized with symptoms of poisoning. While many of the victims, according to the publication, receiving outpatient care have already left the medical facility. Now the causes of leakage of chlorine not reported. As you know, in the report of the independent UN Commission of 1 March 2017, said that during the bombing of Aleppo in 2016, the Syrian air force has used homemade bombs with chlorine. In particular, it was noted that the use of such weapons resulted in the deaths of hundreds of civilians.
The bombs with chlorine only used Syrian air force. It also indicates that the Syrian and Russian planes dropped unguided and cluster bombs.
We will remind, earlier it was reported that the experts of the General mechanism of the Organization for the prohibition of chemical weapons (OPCW) and the UN arrives in Syria to investigate use of chemical weapons in the Syrian Idlib on 4 April 2017.