Parkland.

On April 20, 1999, two teenage boys dressed in black trench coats went on a killing rampage at Columbine High School in suburban Denver.

The 12 students and one teacher killed in the Columbine High School shooting were remembered in a vigil on the eve of the 25th anniversary of the tragedy.

A quarter of a century after the Columbine High School shooting, the trauma from the attack has remained with survivors.

As the small Texas city of Uvalde struggles to heal after a gunman killed 19 children and two teachers at an elementary school, thoughts have also turned to making sure the school’s legacy as the place that was at the heart of a fight for the equal education of Mexican Americans over half a century ago is carried on.

Fourteen mass shootings at U.S. schools since 1999's massacre at Columbine High School in Colorado have killed a total of 169 victims.

Local 4's Nick Monacelli visited with survivors of the 1999 Columbine massacre to hear their experiences and advice as Oxford students return to their high school for the first time since the Nov. 30 mass shooting.

Students who were making plans to attack schools showed the same types of troubled histories as those who carried them out. The study by the Secret Service’s National Threat Assessment Center is a twist on the study of school shootings. It's a companion report to its study in 2019 on student attackers, the most comprehensive analysis of school shootings since the 1999 Columbine High School killings. One-third conducted research into previous school shootings, like the 2012 Sandy Hook Elementary School attack in Newtown, Connecticut, where 27 people, mostly first-graders, were killed. Ad“First and foremost, targeted violence is preventable if communities can identify warning signs and intervene,” Driscoll said.

On Wednesday, Reinfeld was reeling from the latest mass shooting even closer to home, after authorities say a 21-year-old gunned down shoppers at a local grocery store. “I could see at some point leaving because of all this,” said Reinfeld, a gun control activist. But it's also been haunted by shootings that have helped define the nation's decades-long struggle with mass violence. The Aurora shooting brought that terror from schools to a movie theater. After each of Colorado's biggest massacres, the local gun control movement has gained heartbroken new recruits.

"School shootings are becoming normalized. This is Rozenblat's new reality, because she knows exactly what it's like to learn her child survived a school shooting. She pointed to the 2012 school shooting in Newtown, Connecticut, where 26 people were killed. "If kindergartners can die in a school shooting," Norton said, "that means school shooters don't discriminate." "We're left to do what we can to deal with the possibility of a school shooting, and a school can only do so much," she said.

Instead, the Littleton, Colorado, high school, where about 1,700 students in grades 9 through 12 are currently enrolled, will implement "changes to enhance the security and privacy of the site, including the creation of an improved and defined perimeter around the building," he said. The discussion about replacing the original school was driven "by the number of 'unauthorized individuals' (some 2,401 as reported in the Colorado Sun) who came onto Columbine's grounds this past school year," stated Glass. In April, for example, the FBI reported that a high school student who was "infatuated" with the Columbine shooting had traveled from Florida to Colorado and made credible threats. The survey raised the question: "Should we rebuild Columbine High School, further back from the street on which it presently sits, and redesign the building so as to remove the attraction as the site of the 1999 murders?" "Similarly, 55% felt that a potential Columbine rebuild was 'not really important' or 'not important at all'."