Sniper aka The Deadly Tower (1975)
Plot: Charles Whitman is student at the University of Texas in Austin. He often suffers from headaches, during which he tends to violence. One night, he kills his wife and mother, buys a number of rifles and loads of ammunition and takes them to the top of the tower of the university, where he barricades himself. With his long-range weapons his starts to shoot at everything that moves. Already until the police arrives, there are numerous people wounded or dead.