turn off the ignition grab the wheel if the emergency is between the seats pull it on get help from an passer by keep the air way open so that they don't choke. it may pass .
Well I guess I would try to remain as calm as possible. Grab the wheel hit the brakes pull off the road, then shift it into park. Call 911 on the cell, if for no other reason but to make me feel better. Cuz I am probably scared out of my mind..