The smoke began to fill the second-floor corridor, but remained unnoticed for a few minutes. At approximately 2:25 p.m., three eighth-grade girls, Janet Delaria, Frances Guzaldo, and Karen Hobik, returning from an errand, came up a different staircase to return to their second-floor classroom in the north wing (only Delaria would survive the fire). The girls encountered thick grayish smoke, making them cough loudly. They hurriedly entered the rear door of Room 211 and notified their teacher, Sister Mary Helaine O'Neill.