Stream of consciousness rationale: To answer the above question, the relevant sentence is: Just as the soldiers are leaving, a shot is heard, and Tuzenbach's death in the duel is announced shortly before the end of the play.
The question and answer pair are described below.
Q: In the fourth and final act, outdoors behind the home, the soldiers, who by now are friends of the family, are preparing to leave the area. A flash-photograph is taken. There is an undercurrent of tension because Solyony has challenged the Baron (Tuzenbach) to a duel, but Tuzenbach is intent on hiding it from Irina. He and Irina share a heartbreaking delicate scene in which she confesses that she can not love him, likening her heart to a piano whose key has been lost. Just as the soldiers are leaving, a shot is heard, and Tuzenbach's death in the duel is announced shortly before the end of the play. Masha has to be pulled, sobbing, from Vershinin's arms, but her husband willingly, compassionately and all too generously accepts her back, no questions asked. Olga has reluctantly accepted the position of permanent headmistress of the school where she teaches and is moving out. She is taking Anfisa with her, thus rescuing the elderly woman from Natasha.

Answer this question based on the passage: who dies at the end of three sisters?
A: Tuzenbach