The cabin pressure would be at the highest level (attained during the flight) since the aircraft just reached cruising altitude when the "event" happened.
Edit: Pictures of the rear fuselage (taken from the air) show a complete absence of the horizontal stabilizers. The rudder is detached as well. This is a strong indication about problems in the tail area and pictures showing the aircraft with hydraulic leaks in the same section can be a clue as well.
My take based on available pictures is that the event involved a ruptured rear pressure bulkhead followed by a loss of the rudder and stabilizer separation (or failure of the stabilizers independent of the bulkhead).