Families of those who died in one of the deadliest mass shootings in U.S. history visited the site of the massacre at Marjory Stoneman Douglas High School Wednesday for the first time since Nikolas Cruz slaughtered 17 people more than five years ago. 

The Florida school district plans to demolish the three-story building, which has been sealed off as evidence since the Feb. 14, 2018, rampage, when Cruz opened fire, killing 14 students and three staff members.

Four families were escorted through the building, where walls and classrooms are still stained with blood and floors littered with deflated Valentine's Day balloons and wilted flowers.

"I needed to see where my son was murdered," said Linda Beigel-Schulman, whose son, geography teacher Scott Beigel, was shot while directing his students to safety.

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Mother of murdered Parkland teen, inset, Parkland HS larger image

Linda Beigel-Schulman, whose son was murdered in the Parkland shooting Feb. 14, 2018, toured the building with other victims' families for the first time Wednesday. She spoke to reporters after the heart-wrenching visit. (Terry Spencer/ AP)

"I needed to see where he tried to close the door that saved 31 of his students. I needed to be where my son took his last breath," the shattered mother said of the slain 35-year-old. 

Beigel-Schulman took mementos from her son's classroom, including his sunglasses and his lesson plan. 

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Tony Montalto, who lost his 14-year-old daughter Gina in the massacre, said walking into the building was one of the most difficult things he had ever done.

"My firstborn. My only daughter. My beloved," he said. 

Nikolas Cruz, right inset, Stoneman Douglas HS main image

A photo combination of Nikolas Cruz, inset, and the Marjory Stoneman Douglas High School building, where 17 people were murdered Feb. 14, 2018, in a mass shooting. (Associated Press)

The building was preserved as evidence for the separate trials of Cruz and the school's on-campus deputy Scot Peterson, who was acquitted last month for failing to stop him during the six-minute attack. Cruz was sentenced to life in prison.

Prosecutors and family argued that if Peterson had gone into the building, he could have shot Cruz. 

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Beigel-Schulman said that if Peterson had delayed Cruz by 15 seconds, her son could have barricaded himself inside his classroom and survived.

Peterson's attorney, Mark Eiglarsh, has called him a "hero" who did everything he could but was not able to pinpoint the source of the gunfire. He took cover in an adjacent building. 

Scot Peterson celebrates after acquittal

Former Marjory Stoneman Douglas High School deputy Scot Peterson reacts June 29, 2023, after a jury acquitted him of failing to stop Parkland school shooter Nikolas Cruz from slaughtering 17 students and teachers. (Amy Beth Bennett/South Florida Sun-Sentinel via AP, Pool)

More families are expected to take the heart-wrenching private tours in the coming weeks, as well as some of the 17 people who were wounded in the ambush. 

The building, which is visible to the school's 3,000 students as they come and go, has loomed over them as a constant reminder of the tragedy

Five students' families, who are part of a civil suit against Peterson, have requested a reenactment of the shooting at the building, but a judge has not ruled yet. 

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After the tour, Beigel-Schulman, weeping, told reporters that she had tried to say goodbye.

"It has been five years and 151 days, it's been 1,961 days and I still can't say goodbye," she said.

The Associated Press contributed to this report.