It was three years ago that a disgruntled worker opened fire on employees, killing five people: Clayton Parks, Trevor Wehner, Russell Beyer, Vicente Juarez and Josh Pinkard.
Aurora shooting victims: What we know about those killed in Henry Pratt warehouse shooting
Five police officers were also hurt in the attack before they shot and killed the gunman.
Aurora Mayor Richard Irvin is scheduled to speak along with other public safety chiefs.
The ceremony begins at 4 p.m. at the Aurora Historical Society.