The next morning, Gladden left home with a black Bob Marley drawstring backpack. The shotgun was inside, along with a bottle of peanut-butter-and jelly-flavored vodka.
He went to his first three classes before heading to lunch at 10:25 a.m. At a cafeteria table, he told friends that he had a shotgun, but they told investigators they did not believe him. Gladden opened his bag and showed off the weapon to at least one student. That student, a friend, later saw Gladden putting shells in his pocket.
He told police that he implored Gladden not to do anything with the gun. Gladden only told him to leave the cafeteria 10 minutes early.
At some point during lunch, someone threw a paper towel at Gladden's head, prompting him to turn around to a nearby table of boys. "You're dead," he told them, according to one student's account. Gladden then left the cafeteria and headed to a bathroom.
Two students who had been sitting with Gladden got up to leave the cafeteria but were stopped and questioned by two teachers, Holly Cebliak and Richard Rosenthal. One told the teachers, "I can't do this right now. I can't talk about this right now," then hurried through the gymnasium doors and out of the school.
The other student listened to the teachers and returned to the cafeteria.
Several boys from the nearby table also got up to see what Gladden was up to. In the bathroom, one boy noticed what looked like big wooden paddle sticking out of Gladden's waistband.
The shots would ring out just moments later.
'Put it down'
Several people, including guidance counselor Jesse Wasmer, told investigators that they noticed Gladden's neon green T-shirt and his long black hair that day.
Wasmer also noticed something beneath the teen's shirt. He wasn't sure if it was a real gun at first, but then he saw Gladden draw it to his hip.
"I start walking over to him and then I hear a shot and then I start running over at him. This is when my adrenaline starts kicking in," he told a detective that day, still visibly shaken in the recording. Wasmer has not spoken publicly since the shooting.
Wasmer tackled Gladden, wrapping his arms around him as several other adults piled on. The split-second confrontation was captured by security cameras, and one chilling image released to the public shows Wasmer confronting the teen, Gladden falling back while still holding the gun.
"We're all saying, 'Put it down. Do you have anything else?'" Wasmer said. "He didn't actively resist." Another staff member pulled the gun from Gladden's grip.
Some students thought the first shot was just someone "messing around," one wrote in a witness statement. Another student thought it was somebody opening a can of soda or a bag of chips.
School staff member Rita Weber watched the scene unfold from near Borowy's table, yelling for students to "get down."
As she attempted to guide Borowy away from the table, Weber touched his back and found it covered in blood. Another adult pulled him to safety on the ground.
One student near Borowy wrote in her witness statement to police, "I looked to my right and I saw a student with a bloody back. … After a few seconds I heard someone say to get out and I ran out of the back door."
"All I see are students running like crazy people and some people hiding under tables," another student wrote.
Students had abandoned half-eaten lunches and left backpacks stowed under the tables. Outside, photos show that the crowd knocked over trash cans. Somebody lost a pair of black Nike sneakers in the rush; someone else left behind leopard-print ballet flats.