Assad (government) air strike hit a rebel stronghold, as they have done for years. But the strike yielded a mild chemical cloud. Foreign reporters at the scene of the strike found hundreds of begs of chemical that can be used to make weapon, along with piles of detonators. The chemical bombs not yet made, but the air strikes blew up some of the bags. You can find their field reports along with video online. 

The rebels, who recently conducted attacks in Damascus, are making chemical bombs. This is a repeat of the last chemical incident where such bombs were actually used. On that incident, Obama was quick to blame Assad, and vowed U.S. military invasion of Syria (pushed by the Pentagon obviously). Russia intervened and arranged shipment of chemical out of Syria for destruction, defused the incident. It was at this point Obama and his gang develop insane hatred of Putin. Obama wanted war, Putin stopped him. Later, reporters found that the chemicals were sent over by the CIA from Libya.