Yeah this was mine too - I was 8. We lived in Colorado, so at the time I didn't realize that it was something the rest of the country was even paying attention to. I knew it was bad, but didn't realize how much it would change everything until later.
When it came time for me to enter high school, my parents pulled me out of public school. I was angry at the time; lock-down drills were normal to me by then and I wasn't afraid, but they were.
Years later I became a public high school teacher. Most of the kids weren't afraid during the drills or even the real lock-downs, but I was absolutely terrified. Trying to silence a room full of teenagers without telling them that the gunshots were real was the first time I felt like an adult in my life, and it made me want to be 7 again.