Unless they went halfway down the air bridge then down the steps and out the door. Usually happens when the air bridge is u/s.
Looking at shots of AGP, and the video in post #33, the airbridges have the usual escape stairs right at the end, just before you turn left to board the aircraft.
Clearly that's not the stairway being referred to in the reports - 29 passengers standing on those steps would be bl**dy obvious to everybody (and would have been free to descend to the apron, causing chaos and confusion all around).