Ronald Troyke, 59, opened fire on police officers in Arvada's Olde Town Square on June 8, 2021, killing Officer Gordon Beesley in what investigators say was a premeditated attack. Troyke had spent the morning watching YouTube videos about police misconduct and left a note vowing to kill as many officers as possible. He carried 153 rounds of ammunition and multiple weapons to the scene.

Officer Beesley, normally a school resource officer known for his work with special-needs students, was shot while responding to a suspicious person call. The officer was heading to his son's birthday celebration when Troyke ambushed him. Three other officers engaged Troyke from inside a nearby office building as he continued firing at police vehicles and taking cover behind obstacles.

Civilian Johnny Hurley, shopping at a military surplus store, also responded to the shooting by drawing his own handgun. Arvada police had extensive active shooter training due to Deputy Chief A.J. DeAndrea's experience responding to Columbine and other mass shootings. The department required triple the state-mandated training hours for officers.

The incident marked the first line-of-duty death in Arvada's history and highlighted the community's tragic familiarity with mass violence. Troyke's manifesto criticizing police corruption and his methodical preparation revealed a calculated attack on law enforcement in a city that had worked extensively to prepare for such threats.