This happened a few years ago, in my former school. As that was school opening. a freshman girl entered the the comfort room to fix herself. while facing the mirror she saw a lady wearing the uniform of a CAT officer, thinging that she was an student of that school and that she was an officer she smiled at her, the lady smiled back.
After that incident she she always saw tht lady around the campus still wearing the Officer uniform, and everytime they meet they exchanged smiles. One day while in the canteen she saw the lady again. she smiled at her the lady also smiled. then another student passed by, to her surprise the student passed through the lady officer, she fainted. her classmates bruoght her to clinic, when she woke up she was hestirical. then she was brought to the guidance office. when the counsellor ask her what happened, she told him about the lady, the counsellor gave her school records, then she saw the picture of the lady, the counsellor, was shocked then he told the student that the lady she saw died already a year ago because she dround during their military ball