Thousands of students across the U.S. walked out of class to mark a school shooting that occurred nearly two decades ago, and to call for stricter gun control in the wake of more recent shootings.
The nationwide walkout was organized by students at Marjory Stoneman Douglas High School in Parkland, Florida, where 17 students and staff members were killed by a former student February 14.
WATCH: US Students Mark 1999 Colorado School Shooting Anniversary with Walkout
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US Students Mark 1999 Colorado School Shooting Anniversary with Walkout
The Parkland massacre triggered a national grassroots campaign for more restrictive gun control laws that included recent marches in Washington and in other cities and towns throughout the United States.
Washington area high school students rallied at the White House before marching on Capitol Hill to demand action from lawmakers.
They joined students from more than 2,600 high schools and other institutions across the country who walked out of class, many wearing orange, a color that has come to represent the gun control movement.
Several hundred students march to a rally on the West Lawn of the Capitol in Washington to call for an end to gun violence in schools, April 20, 2018.
Friday's activities were in commemoration of the April 20, 1999, mass shooting at Columbine High School in the western state of Colorado, when two students roamed the school, killing 12 of their classmates and a teacher before committing suicide.
Gun rights supporters held counter-demonstrations in some locations. The Associated Press reported that about 200 people rallied outside the Kansas state capitol in Topeka, and about 30 pro-gun protesters showed up outside the New Hampshire statehouse in Concord.
Friday also saw another shooting take place at a U.S. school, when a gunman shot at a closed classroom door and wounded a student at Forest High School in Ocala, Florida.
Police say the 19-year-old shooter, who brought a shotgun into the school in a guitar case, was a former student. He was arrested at the scene.
The victim, a 17-year-old boy, was treated at an area hospital for a wound to his ankle.