Both Tu-154 B and M do not have automatically deploying slides as western airliners have. The slide should be manually taken out of the box, fixed in the doorway, thrown down, and then by pressing the handle its inflation should be activated.
In this case the stewardess was not able for quick decision of required evacuation, and tried to calm down the passengers and asked them to sit back on the seats, however, people from the back side of the plane pressed forward and soon the stewardess was swept far from the exit by the crowd. No one of passengers of course didn't know how to deploy the slide, and when it became really bad, they started jumping from the 3m height.
The slide from the first exit was deployed by the Flight Engineer.