The Worst Mass Shooting In US History

The Worst Mass Shooting in U.S. History: A Retired Las Vegas Police Officer Shares His Story. On October 1, 2017, the world witnessed the deadliest mass shooting by a lone gunman in American history. More than 22,000 people were gathered for the Route 91 Harvest music festival on the Las Vegas Strip when gunfire erupted from the 32nd floor of the Mandalay Bay hotel. In just ten minutes, a 64-year-old attacker fired over 1,000 rounds into the crowd, killing 60 people and wounding hundreds more. The total number of injured would eventually rise to approximately 867 as panic swept through the venue.