The cell door closes, and it clicks shut, clearing locking. Gilchan looks at you, then at the madman, and yells "Now, Kliathe!"
The madman leans his chest toward his chained left arm, which reaches, fingers digging into his own flesh, and he yanks. A gobbet of chest flesh peels away, revealing a shiny object within. A flash of blood magic occurs, and suddenly, every prisoner in the jail looks identically like a guard you haven't seen. They reach out quickly and push the doors, which all open! They crowd into the hallway and reach for you and your weapons.
Below, I'll roll for initiative for two groups, which will become apparent later. I'll post initiative order after that. The spell casters can make an Arcana (Spellcraft) check as a free action on their turns to identify what happened, if they wish.
Rolls
Initiative group 1 - (1d20+2)
(8) + 2 = 10
Initiative group 2 - (1d20)
(7) = 7