Abstract: A locking and unlocking device for opening an emergency exit in which an anti-panic bar is supported, at its ends, by two arms rotating in housings fastened by their bottoms on the leaf of the exit, on each side of the bar, one of the housings including the actual lock and the other including a horizontal finger extension from a lever of the anti-panic bar on the other side of the axis of rotation of the lever toward the bottom of the housing, a slide supported on the finger and vertically movable, whose front upper edge has the shape of a step, the side of the step being almost vertical and the base of the step slightly inclined forward, a transverse rod movable between a rear position where it abuts against the side of the step, slightly above its base, when the slide is in a low position, and a forward position where it is in front of the slide, a return device being provided for the rod in the forward position, the transverse rod being carried by the lower arms of lateral small rods rotating about a trans