Twenty years ago, 13 people were killed when two teenage boys dressed in black trench coats killed a teacher and 12 students and wounded dozens of others.
The crosses of the 13 people who died in the Columbine High School massacre 20 years ago in Colorado highlight those who were killed in 1999.
A remembrance ceremony honoured their lives on Saturday. It was part of a week-long series of events.
Nikki Johnson lives in Columbine and said, "I would have loved to say that things have changed, that we've learned but we have not. I just don't know what else to do except educate them and try to create better people and more empathetic people."
In 1999, two teenage boys, dressed in black trench coats killed a teacher and 12 students. They were just three weeks shy of graduating.
They wounded two dozen others before taking their own lives.