The 1200 building at Marjory Stoneman Douglas High School in Parkland, Florida, has been a lingering reminder of one of the worst mass shootings in U.S. history for more than six years.

The building had remained untouched since 2018 when a gunman killed 14 students and three staff members on Valentine's Day. But after being preserved as evidence for the shooter's trial, crews are set to tear down the three-story building by pieces starting Friday.

The demolition was scheduled to begin Thursday morning but was postponed by heavy rain and flooding. The building, which people who have toured it described as a time capsule with bullet holes and bloodstains still visible, was closed after the shooting and fenced off as crime scene evidence.

Officials said the demolition is expected to take several weeks. School officials have yet to announce what the building will be replaced, with but students, teachers, and families have suggested a permanent memorial be put in place.

Victims’ families were invited to observe the demolition, officials said. They were given a designated viewing area on school grounds.

"The demolition of the building where my daughter Gina and so many others lost their lives is a necessary part of moving forward," Tony Montalto, president of Stand with Parkland, said in a statement to USA TODAY. "Tearing down the 1200 building at Marjory Stoneman Douglas High School will not erase the fact that the worst high school shooting in US history occurred here. Seventeen beautiful lives were tragically taken because a multitude of simple school safety procedures were not prioritized."

Other schools have closed and demolished buildings after a mass shooting. After the shooting in 2012, the old Sandy Hook Elementary School was torn down and reopened in 2016. Officials announced in 2022 that they planned to demolish Robb Elementary School in Uvalde, Texas.

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Aftermath of Parkland high school shooting

Despite calls to destroy the old freshman building after the shooting, officials ordered it to remain until the gunman's trial ended in 2022.

Prosecutors had jurors take a rare tour of the crime scene. They saw bloodstains on the floor, bullet holes in the walls, fragments of glass from shattered windows, and students' homework and Valentine's Day gifts left behind in the chaos.

The shooter, Nikolas Cruz, was sentenced to life in prison without the possibility of parole in November 2022. He had been charged with 17 counts of murder.

Family members of the victims were angered and disgusted by the jury's decision. Prosecutors had sought the death penalty, but a death sentence requires a unanimous vote on at least one count under Florida law, The Palm Beach Post, part of the USA TODAY Network, reported at the time.

The building also was used in a reenactment of the shooting last August as part of a civil lawsuit against former Broward County school resource officer Scot Peterson, who was accused of failing to protect students. Ballistic experts used an AR-15-style semiautomatic rifle identical to the one Cruz used.

The lawsuit, which was brought by some of the victims' families, claimed Peterson had neglected his duty by not entering the building or engaging with the gunman. Peterson has said he stayed outside because he was unable to determine where the gunshots were coming from.

In a separate criminal case in June 2023, Peterson was acquitted of 11 counts of child neglect, culpable negligence and perjury.

'Create a space that honors their legacy'

The Parkland shooting sparked a widespread movement over gun control legislation and public safety reform. In the wake of the tragedy, the student-led organization March for Our Lives was created.

March for Our Lives was founded by teens who survived the shooting, and since then, hundreds of demonstrations connected with the organization have taken place across the country. In 2018, more than 1 million people rallied in Washington, D.C. Thousands of people also rallied in 2022 to advocate tighter gun control laws after other mass shootings.

Parkland families also launched an advocacy group called Stand with Parkland in 2018. The national organization said it is committed to pushing for "practical public safety reforms focused on the safety of our children and staff at school, improved mental health support, and responsible firearms ownership."

The organization has worked with state and local officials to raise awareness of school safety and has been instrumental in many bipartisan actions.

"While we can never erase the pain and the memories, we can create a space that honors their legacy and fosters hope for a safer future," Montalto said. "That’s why we fight every day to pass meaningful legislation that keeps our family members safe in their school."

Contributing: Hannah Phillips, Palm Beach Post