On August 1, 1966, the University of Texas at Austin was rocked by an early episode of mass campus violence when a gunman, later identified as Charles Whitman (who had killed his wife and mother earlier in the day) began firing randomly at people from the tower that dominated the square. As Keith Maitland’s imaginative documentary demonstrates, even after the passage of fifty years the horror of that day, when fourteen (including an unborn child) were killed and thirty-two others wounded over the course of less than two hours before police managed to reach the observation deck and end the assault, is ingrained in the memory of survivors. The film also situates the tragedy in the context of later mass school killings—a litany of tragedies that seems endless.

Maitland combines “they were there” and “you are there” elements by embracing a variety of cinematic techniques. On the one hand he’s assembled an array of archival materials—radio reports, television clips and footage of the site itself during the event. He adds to that interviews with those in the line of fire (some vintage, others new) as well as reenactments, sometimes in terms of voiceovers and sometimes recreations of action; but while portions are shown directly on film, many are done via rotoscopic animation, endowing them with a shimmering, hallucinatory vibe. An overlay of period music completes the effect.

Within that general pattern, a few story threads stand out. One centers on Claire Wilson, the pregnant woman who was the first person shot as she walked through the quad with her boyfriend Tom Eckman. He was killed immediately after, and she lay on the hot cement, comforted only by another student who put herself in harm’s way by lying down beside her, until rescue came. That was in the form of two young men, John Fox and James Love, who ventured from their hiding place to carry her to safety, and whose story of coming to the site when they heard initial reports about the shootings (wrongly attributed at the time to an air rifle) is another major plot element. (Wilson and Fox are newly interviewed, and are brought back together in one poignant sequence. The film also pauses to give attention to Eckman’s memory.)

Then there’s the story of Aleck Hernandez, who was shot while on his bike delivering papers, with his younger cousin riding along with him (the two are reunited in a contemporary interview after many years apart). Another thread follows Allen Crum, the manager of the campus bookstore, who rushed from the safety of the building to tend to Hernandez and then ran to the base of the tower to enter the structure.

Crum’s story dovetails with those of the two policemen—Houston McCoy and Ramiro Martinez—whom he joined to ascend the stairs and confront Whitman. (Martinez offer his recollections in a new interview, while the deceased McCoy is seen in archival testimony.) The sequence of them finally ending the siege (with Crum waving a white handkerchief to indicate their success to the people below, some of them cops and civilians who continued to shoot in his direction) creates considerable tension, even though we all know how it will end.

Acting as a unifying mechanism throughout are the reports of Neal Spelce, the young newsman whose reports from the scene were picked up nationally. We hear those reports, but he also recalls the day in a new interview, at one point tearfully remembering how a colleague of his who’d come out of retirement to take over hosting duties back at the station was stunned when his own grandson was named as one of the dead.

Maitland’s skillful assemblage of material gives his recounting of the terrible event remarkable immediacy while also endowing it with nightmarishly universal meaning. We feel for the individuals trapped in this awful incident, but are led inexorably to think about those caught up in other similar tragedies as well. “Tower” is an impressive piece of innovative documentary filmmaking.