The truth in the gas explosion is far from clear. The "moderate" rebels are ISIS by any other name. Here is an eye-witness to the "rebel" bombing of buses carrying civilians to safety:
https://www.youtube.com/watch?v=uR83CFhKoSw
And as reported by Canadian journalist Eva Bartlett:
"..the anguished rhetorical question one asks in such repeated situations: “Where are the mainstream media? Why don’t they report the barbaric and cowardly terrorist attack on Foua and Kafraya?”
The answer is that the genuine torment these civilians have endured for years will never be fairly reported, it does not serve the agenda of demonizing the leader of Syria and the national army in order to win western public opinion for yet another ‘humanitarian’ intervention which destroys the Syrian nation and installs chaos in the place of the legitimate government."
excerpt from https://ingaza.wordpress.com/2017/04/15/no-red-lines-after-western-backed-terrorists-massacre-of-idlibs-foua-civilians/