Although I only have 20 hours as a jump pilot... Here's what I would do. I would Immediately slow the airplane down, and start down. NOBODY LEAVES THE AIRPLANE!!!!! Especially if there are people to block the air inside the airplane. At the same time, tell everyone to get ready incase something bad happens. (Including myself). Get a plan of escape if something should happen. Take off the seatbelts? I don't know... maybe... Essentially the main point to be stressed would be for me to slow the airplane down, and to have that PC darn near bolted to the airplane. If somebody jumped in this situation without my ok, I would probably deny them a flight on my plane ever again. Be safe!!!