(CNN)Emma Gonzalez, a student and survivor of the Parkland, Florida, stood on stage at the March for Our Lives for 6 minutes and 20 seconds.
Emma Gonzalez stood on stage for 6 minutes - the length of the Parkland gunman's shooting spree
"Six minutes and about 20 seconds," she said. "In a little over 6 minutes, 17 of our friends were taken from us, 15 were injured and everyone in the Douglas community was forever altered."
"Everyone who was there understands. Everyone who has been touched by the cold grip of gun violence understands. For us, long, tearful, chaotic hours in the scorching afternoon sun were spent not knowing. No one understood the extent of what had happened."
"No one could believe that there were bodies in that building waiting to be identified for over a day. No one knew that the people who were missing had stopped breathing long before any of us had even known that a code red had been called."
It only took 6 minutes and 20 seconds, Gonzalez said, for a gunman and an AR-15 to extinguish the lives of the 17 students and faculty had died. She repeated the names of each of the victims and the things they would never do again.
Then, she stopped speaking. Silence gripped Gonzalez as tears rolled down her cheeks, and the crowd broke through with random chants. But mostly, silence.
After 4 minutes and 25 seconds, a timer went off.
"Since the time that I came out here," she said, "it has been 6 minutes and 20 seconds. The shooter has ceased shooting and will soon abandon his rifle, blend in with the students as they escape and walk free for an hour before arrest."
"Fight for your lives before it's someone else's job," she said, and left the stage.
Saturday night, after the march ended, Gonzalez took to Twitter to explain that her speech and the moment of silence combined clocked in at about 6 minutes and 30 seconds.
"Imagine how long it would have felt if (the silence) actually was 6 minutes," she wrote, "or how it would feel if you had to hide during that silence."