Who attempts to stop the violent argument in Chapter Six? What happens?

Nancy comes downstairs and tries to convince Lou to put down his weapon. Hank is hopeful that Nancy's calming presence will put an end to the volatile situation, but Lou shouts at her to go back to bed and says that he's going to shoot the other two. Just then there's an explosion, and Lou is suddenly gone from Hank's sight, blown back through the door by Jacob's shot.