Iosef, Ravenath and Anaerion (Making an assumption here to move things along) each move to one of the switches discovered earlier. On the signal, they flip their levers simultaneously and the door opens without any action from Kalgor. As the three of you are moving back toward the exit, however, Kalgor sees the door beginning to close again. Moving quickly, he puts out a hand and stops it.
The wailing grows in volume as the door opens, revealing a hallway going south 5' before splitting east and west.