Survivors of the Columbine High School massacre have led solemn services marking the 10th anniversary of the tragedy that left 13 people dead.
In the Denver suburb of Littleton, 1,200 people gathered to reflect on the horrific events of 20 April, 1999, when teenagers Eric Harris and Dylan Klebold went on a bloody rampage.
Thirteen white doves were released following a sombre outdoor ceremony at a park just a short distance from the scene of one of the most traumatic school shootings in US history.
Columbine's principal Frank DeAngelis said students on campus during the attack had been robbed of their childhood.
"You were forced to grow up far too quickly. I wish I could wipe away the tears you shed," Mr DeAngelis told the crowd.
Val Schnurr, who was shot in the attack, said while the events of 1999 remained vivid, she refused to consider herself a victim.
"As a survivor, there are days it feels like it happened yesterday," Schnurr told those assembled.
While Columbine became a catalyst for a national debate about gun control in the United States, where the right to possess firearms is enshrined in the constitution, attempts to restrict weapons have largely fizzled.
The administration of former President George Bush did not renew a 10-year moratorium on the sale of assault rifles that expired in 2004.
President Barack Obama's administration has said it plans to renew the ban, a pledge that appears to have caused soaring sales of firearms since last year's election.
But recent polls suggest that support for stricter laws on gun control is at an all-time low, with a CNN survey showing just 39% in favour of more restrictions compared to 54% eight years ago.