At approximately 10:22 a.m., an anonymous man phoned the 16th Street Baptist Church. The call was answered by the acting Sunday School secretary: a 14-year-old girl named Carolyn Maull. To Maull, the anonymous caller simply said the words, "Three minutes", before terminating the call. Less than one minute later, the bomb exploded as five children were present within the basement restroom, close to the stairwell, changing into their choir robes in preparation for a sermon entitled "A Rock That Will Not Roll". According to one survivor, the explosion shook the entire building and propelled the girls' bodies through the air "like rag dolls".