Once on school grounds, the 19-year-old donned a tactical vest and gloves inside a campus bathroom - before firing one round through a classroom door, which wounded a 17-year-old student.
Within minutes, a school resource officer on campus found a 17-year-old student who had sustained non-life-threatening injuries.
The shooting happened at Forest High School at 5000 SE Maricamp Road in Ocala, Fla., which was placed on lockdown.
Since then, a number of the student survivors have gone on to become outspoken gun-control activists, organising the nationwide March for Our Lives event as well as monthly school walkouts.
An alleged school shooter made his first appearance Saturday morning in Marion County.
Craig Ham, deputy superintendent of Ocala schools operations, said the gunman carried the shotgun in a guitar case into the school by blending in with students.
He fired a single shot into a door, hitting a 17-year-old boy in the foot.
He ignored most of the other questions until asked what he'd say to the shooting victim. "Society has changed since I was in school".
Bouche showed little emotion as he stood before a Marion County judge. He then began researching different types of mass shootings and chose to target a school because he thought it would gather more media attention.
"The fact that it happened on this day, in a way, reinforces what we are trying to get across", said Ryan Servaites, a high school freshman in Parkland, Florida, where 17 students and teachers were gunned down in February. Parkland students are participating in the national walkout - which is also the 19th anniversary of the shooting deaths of 13 people at Columbine High School in Colorado.
Forest High, which was ranked as one of the best high schools in the nation by U.S. News & World Report, has about 2,100 students.