The first big act of mass murder in the modern United States of America occurred on August 1, 1966, at the University of Texas at Austin.
The perpetrator, 25-year-old Marine veteran Charles Whitman, indiscriminately fired at members of the public both within the Main Building tower and from the tower's observation deck.
He shot and killed 15 people, including an unborn child, and injured 31 others before he was killed by two Austin Police Department officers approximately 96 minutes after first opening fire from the observation deck.
Prior to arriving at the University of Texas, Whitman had stabbed his mother and wife to death—in part to spare both women "the embarrassment" he believed his actions would cause to them!
At the time, the University of Texas tower shooting was the deadliest mass shooting by a lone gunman in U.S. history, being surpassed 18 years later by the San Ysidro McDonald's massacre.
It remained the deadliest school shooting in American history until it was surpassed 41 years later by the Virginia Tech shooting.
"Praise the Lord and pass the ammunition!" (The home of the brave and land of the free... to do whatever you want!)