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Media captionSamantha Haviland was a student at Columbine High School when the 1999 shooting happened
Survivors of the Columbine High School shooting have been speaking at a remembrance ceremony in Denver to mark the twentieth anniversary of the massacre.Twelve students and a teacher were murdered by two teenagers. One former student, Patrick Ireland, who was injured by bullets, said no one from the school or surrounding community had emerged unscathed. The event was the culmination of three days of commemorations. Earlier, members of the public left flowers and cards at a memorial to the victims.
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Media captionBill Clinton spoke at the remembrance ceremony via video link
Columbine students and staff also marked the day by taking part in community service projects.
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Survivor Will Beck placed flowers at the Columbine Memorial at Clement Park in Littleton, Colorado
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Sean Graves, a massacre survivor and 2002 graduate, spoke during the ceremony
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Crosses with the names and portraits of the victims at Chapel Hill Memorial Gardens, also in Littleton, Colorado
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People gathered to remember loved ones at the Columbine Memorial
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Spencer Greenlee, a student at Columbine High School, sat in prayer at the memorial
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Candles around a collection of flowers laid at the memorial
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Visitors read a poem left at the memorial