Twenty years ago on Saturday, two gunmen claimed the lives of 13 victims and marked the beginning of an era in which the U.S. has repeatedly been forced to reckon with the threat of school shootings. Since the Columbine High School massacre, more than 226,000 students at 233 schools have been affected by school shootings, according to a Washington Post analysis.

On April 20, 1999, two Columbine seniors, Eric Harris and Dylan Klebold, carried out a planned attack at their high school using a combination of firearms and homemade explosives. They shot and killed 13 people — 12 students and a teacher — before turning their weapons on themselves. A memorial was designated in 2007 to honor the victims: students Cassie Bernal, Steven Curnow, Corey DePooter, Kelly Fleming, Matthew Kechter, Daniel Mauser, Daniel Rohrbough, Rachel Scott, Isaiah Shoels, John Tomlin, Lauren Townsend and Kyle Velasquez, and teacher Dave Sanders. The outdoor space, which sits in a park adjacent to Columbine High School, welcomes visitors to reflect on the community’s loss.

This past week, three days of commemorative events were held in their honor, culminating with Saturday’s memorial ceremony in Littleton, a Denver suburb. The events continued despite a threat against the school that arose this past week: On Tuesday, the community faced danger once again after an 18-year-old woman traveled from Florida to Colorado and purchased a pump-action shotgun at a shop near Columbine. The woman, Sol Pais, who had left a trail of disturbing messages online, was found dead of an apparent self-inflicted gunshot wound. The incident heightened already tight security for the week’s events.

In the middle photo, Will Beck, left, a Columbine sophomore during the massacre, reunited with Lee Andres — a teacher who opened a door to allow Beck and other students to escape the shooters — at a Friday vigil. Also in the crowd was Sarah Boyd, who came to lay flowers as she has done every year. “It can happen anywhere. No one is immune, unfortunately,” said Boyd, who graduated from Columbine in 1996. “I hope someday that people can look back and say these are the things that were made better because of such a terrible day.”

Washington post