This is a copy-paste of a post I made on reddit:
I was in second grade, and my class was just sitting down in our school bus to go to the gym building a few blocks away. I looked out the back window and saw the first plane hit. My school was on 6th avenue, so I could see straight down to the WTC. I remember my teacher saying to the class that there had been a little accident and a plane flew into the world trade center. We were so little we didn't really think about the death involved with that. Well, most of us. One of my classmates started crying when she saw it. Turns out her dad worked there, and died that day. The school dedicated a new gymnasium to him.