A high-school student in New York, Sandra Uwiringiy’imana, endured a night of hell when she was a child—a bloody massacre on her tribe in Africa. Many of her fellow survivors are scattered around the U.S., thanks to a U.N. refugee program. Now, every year on the anniversary of the attack, the survivors meet. At these gatherings, Sandra and her brother Alex Ngabo take their portraits. Here is a selection of their photos.