I can't find any confirmation about this incident from the mainstream media channels. However, the pro-SAA Al Masdar News published this article a few minutes back:

https://www.almasdarnews.com/article/breaking-civilians-killed-us-jets-bomb-isis-chemical-depot-deir-ezzor-syrian-mod/

It is no surprise that the ISIS is having chemical weapons. Previously, they have used them against the civilians, the SAA and the SDF.