Experts are inferring what they can from the reports and videos leaking out of Syria in the wake of a possible chemical weapons attack, and what they're saying isn't good. The Washington Post explains that there are seven types of chemical weapons, the deadliest of which are nerve agents—and that's the type that may have been used, per a senior fellow with the Federation of American Scientists. He describes their effects: "There's muscle twitching. Then, as the muscle twitching gets more and more spasmodic, mucus comes out of the nose and mouth and you basically go into convulsions on the ground. People don’t survive this."