The regular actors carry out their scene as they would any others, ideally the scene will be mundane and safe. Stunt doubles can be called in when one player is about to open a door, or comb her hair. The stunt doubles replace the two players and that mundane activity becomes extraordinarily dangerous and harmful.
Some players can do the action in slow motion.
When the stunt is finished usually with some horrid injury to the stunt double, the regular actors come in and continue the scene where the stunt doubles left off. Have the stunt doubles become more and more lame as they come on for each stunt.