The 'black boxes' were recovered though there is a report that the CVR (cockpit voice recorder) was heavily damaged. The CVR usually provides only the final thirty minutes so it would be of little use and most crashes result in more information being obtained from background noises on the CVR than actual cockpit conversation anyway.
The "poison gas" was an unfortunate term to have been used. Perhaps they meant toxic. Such as carbon monoxide. An insidious systemic 'poison'.
Actually, cabin pressurization is provided by bleed air from the engine compressor and it is rare for there to be any sort of fumes unless the engine has recently been started. The bleed air must first be cooled then sent to the air conditioner system and then to the cabin so fumes from jet fuel rarely reach the cabin in any great quantity and certainly not long after takeoff.
Alot of airlines 'skimp' on cabin pressure because use of bleed air means increased fuel costs.
If oxygen masks drop, some passengers hesitate too long. The rule is, even if the plane is sitting on the ground and you KNOW, absolutely KNOW, that you don't need oxygen because you are at sea level and have not even taken off yet, if the masks drop, get them on and do it FAST.
Thats why you put YOUR mask on first and then aid a child you are traveling with. There is no time to aid the child first.
Now it does not look like there was any explosive decompression and the military pilots did not report the sighting of dropped oxygen masks but they made no comments about the interior of the cabin anyway.
My first question would be when was the last engine maintenance? How many flights since then?