WATCH: Parkland survivor confronts Scot Peterson in courthouse elevator. Peterson's reaction says it all.

Kyle Kashuv, a survivor of the tragic massacre at Marjory Stoneman Douglas High School, confronted former Broward County sheriff's deputy Scot Peterson — the school resource officer tasked with protecting MSD students and faculty — in a courthouse elevator Tuesday.

What is the background?

Peterson was at the Broward County Courthouse to give a deposition in a civil lawsuit brought by Andrew Pollack, whose 18-year-old daughter, Meadow, was tragically murdered in the February 2018 massacre.

Pollack filed a wrongful death lawsuit last April alleging negligence on Peterson's behalf after it was revealed he failed to act appropriately to confront the killer. In the massacre's aftermath, surveillance footage surfaced showing Peterson taking cover near stairs outside of the school building while the killer murdered 14 students and three teachers inside.

What happened in the elevator?

While riding in the elevator with Peterson, Kashuv grilled the former police officer over his failure to properly carry out his duty by engaging the lone killer.

"Can you explain to me why, like, 17 people died in school? Fourteen kids, 17, while you stood outside with a gun and did absolutely nothing?" Kashuv asked.

Peterson, with his hands crossed in front of his body, stood stoic, almost expressionless, as Kashuv grilled him.

"That was your job, now you are getting paid like $80K a year to stand there while you let those kids die. It's disgusting. It's despicable and I hope that lives with you for the rest of your life. You had a chance to save those kids. You were the one with the job who was supposed to do it — and you didn't," Kashuv said.

"I don't know how you live with yourself every day, man. You were the one who was supposed to go inside. You didn't," he continued. "You know I was a student there that day, in the building right next to it. And fourteen of my classmates are never coming back because you didn't act."

Peterson never responded to Kashuv.

(H/T: Dana Loesch)