There was a press conference today which had the senior flight attendant explaining what happened from her point if view.
She said there was no information given to them from the flight crew, they just noticed it was no normal touchdown and rushed to evacuate once the plane had come to a stop.
From what I understand she quickly moved herself to the overwing aero and opened some of the exits. At least one wouldn't open.
Passengers evacuated quickly and after that the junior flight attendant who was sitting in the back crawled through dense smoke to the front and reported to the captain (or senior attendant) that she saw no passenger on board. She received burns to her head on the way. The captain and this junior flight attendant left the plane by then and it started or was burning considerably by then.
The passenger who ceased did so because she fainted during impact and was left behind, the crew had no chance to notice her then in the smoke.
The senior flight attendant stressed that in her view the evacuation went pretty much as per procedure, and apologized for failing to rescue one passenger.