On the morning of August 1, 1966, not long before summer classes at the University of Texas at Austin were about to let out for lunch, an architectural engineering major named Charles Whitman arrived at the Tower dressed as a maintenance man. He would be described the following day in the Austin American as “a good son, a top Boy Scout, an excellent Marine, an honor student, a hard worker, a loving husband, a fine scout master, a handsome man, a wonderful friend to all who knew him—and an expert sniper.” The footlocker he wheeled behind him contained three rifles, two pistols, and a sawed-off shotgun, as well as a cache of supplies (among them canned peaches, deodorant, an alarm clock, binoculars, toilet paper, a machete, and sweet rolls) that suggested he planned to stay awhile. After a receptionist switched on an elevator that Whitman had been trying in vain to operate, he smiled and said, “Thank you, ma’am. You don’t know how happy that makes me.”

Whitman rode the elevator to the twenty-seventh floor, dragged his footlocker up the stairs to the observation deck, and introduced the nation to the idea of mass murder in a public space. Before 9/ 11, before Columbine, before the Oklahoma City bombing, before “going postal” was a turn of phrase, the 25-year-old ushered in the notion that any group of people, anywhere—even walking around a university campus on a summer day—could be killed at random by a stranger. The crime scene spanned the length of five city blocks, from Twentieth to Twenty-fifth streets, bounded by Guadalupe (“the Drag”) to the west and Speedway to the east, and covered the nerve center of what was then a relatively small, quiet college town. Hundreds of students, professors, tourists, and store clerks witnessed the 96-minute killing spree as they crouched behind trees, hid under desks, took cover in stairwells, or, if they had been hit, played dead.

Both the Associated Press and United Press International would rank the shootings as the second most important story of the year, behind only the war in Vietnam. But until 1999, when the university dedicated a memorial garden near the Tower to the victims, the only physical reminder on campus of what had taken place were the few remaining bullet holes left in its limestone walls. (Many of the original scars had, over the years, been filled in with plaster.) No plaques had ever been displayed, no list of names read, no memorial services held. Decades of institutional silence had turned the shootings, and Whitman himself, into the answers to trivia questions. But, of course, there was nothing at all trivial about that day.

To mark the fortieth anniversary of that day, we asked the people who were there to tell their stories.