What chemical weapons are they you ask?
Why, a chlorine gas supply.
You see, anyone can make chemical weapons. In this case, just mix amonia and chlorine bleach. As any janitor learns on his first day, this releases chlorine gas. This will burn the eyes, nose, throat, and lungs, and can cause a very death.
So, what out for suspicious people loitering in the cleaning supply row. Who you think is just a friendly home owner could be a mad person bent on world terror.