I don’t know what is going on there.

I find it improbable that the Syrians would engage in a massive chemical weapons attack, and while the videos appear to show the use of some sort of nerve agent, but if it was Sarin, the doctors treating the victims should have been exposed as well. 

It does seem to be some sort of appear to be the action of a cholinesterase inhibitor, probably an organophosphate, but it was odd.

The problem is that there a profound lack of transparency here.

It could be the Syrian army launching a massive Sarin attack.

It could be the rebels using Sarin that they are rumored to have gotten from Libyan stockpiles.

It could be some other sort of nerve agent, such as certain insecticides, which would explain why the doctors did not get dosed.  (The toxicity and the secondary contamination characteristics could be quite different, even if the symptoms are largely identical.)

I do hope that the UN team manages to get in and collect samples.