Cameron Kasky is a 17-year-old junior at Marjory Stoneman Douglas High School. He and his brother Holden survived Wednesday's school shooting at their Parkland, Florida, high school. The views expressed in this commentary are his own.

(CNN) I thought it was going to be a wonderful day. My high school, Marjory Stoneman Douglas, was full of cheerful students -- many of whom were celebrating Valentine's Day with one another. Even those who didn't have a Valentine seemed like they could find reasons to smile.

But then, of course, everything changed. Toward the end of the day, I went to pick up my little brother Holden from the special needs classroom. As we exited the school, the fire alarm went off. And as we retreated to the parking lot, per fire drill procedure, we were told to run back inside.

It was very confusing, especially since I was surrounded by special needs students. But the truth is, nobody really knew what was going on. We huddled in a room, listening to terrifying noises we couldn't quite identify, and spent an hour plagued by uncontrolled anxiety ... waiting for answers. Waiting for somebody to either come in and shoot us or come in and tell us everything was going to be OK.

Eventually, the SWAT team came in and did an excellent job taking care of the students with disabilities. We were then escorted to our evacuation location and, after hours of confusion and terror, my brother and I made it home.

Though we made it home, 17 people didn't. Those 17 people were murdered on the grounds of a school that has always felt like the safest place to be in a town that's been called the safest town in Florida

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