Wednesday's allegations of chemical weapons use near Damascus mark a new and very troubling chapter of Syria's ongoing civil war, a conflict that has already killed more than 100,000 people.
But this isn't the first time chemical weapons allegations have been made in Syria.
In April, activists and medical professionals claimed a chemical agent was used in an attack on Kurdish-controlled neighborhood of Sheikh Maqsoud in Aleppo.
GlobalPost's Tracey Shelton was the first reporter on the scene, where she obtained exclusive photos and video of that April attack.
As with so much that is happening today inside Syria, serious questions remain about the precise circumstances surrounding that earlier incident.
Warning: The following video contains graphic images.