The three-story school about 48km northwest of Fort Lauderdale has stood as an empty reminder of the attack on Feb 14, 2018, with bullet holes and bloodstains still visible. Video from an ABC affiliate on Friday morning showed construction vehicles starting to rip into one corner of the structure as dozens of onlookers watched.

The gunman, who was 19 at the time of the shooting and a former student at the school, murdered 17 students and staff and injured 17 others with a semi-automatic rifle. He was sentenced to life in prison but spared the death penalty in 2022.

The school was preserved largely untouched as evidence, first for the gunman’s trial and later for the trial of the school resource officer who was on duty the day of the shooting. He faced charges for not rushing to confront the shooter after the attack began.

A jury acquitted the officer in June 2023.

Since the shooting, the building has loomed eerily over the rest of the campus behind a chain-link fence, seen by successive years of students as they walked to their classes.

Vice-president Kamala Harris walked the halls of the building in March on a visit to remember the victims and push for states to strengthen laws on seizing firearms from high-risk people.

Some of the survivors of the 2018 massacre organised March For Our Lives, a youth-led movement for tighter gun regulations in the US, which has the highest rate of private gun ownership in the world and where mass shootings have become recurrent.

The Broward County School District said demolition would take several weeks and involve dismantling the structure in pieces. It was delayed a day after inclement weather on Thursday.