I'm from NYC and was in 4th grade when it happened.
I was in class and my teacher had this radio on. I remember hearing how a plane hit the world trade center. I used to play Flight Simulator as a kid and thought that a small plane hit it by accident. They'd put out the fire and that's it.
Eventually as the day went by, parents started to come to the school to take their kids home. One by one my classmates would go home. I was thinking to myself "Hey! Maybe i'll get picked up too and leave school early!". Eventually I did get picked up.
On the way home, my mom told me that the "World Trade Center" is gone. I didn't know what she meant by that, I went to visit the towers a few years ago and just saw them on the skyline a week before returning from a trip.
I came home and finally saw what happened on TV. I didn't have cable TV and we watched TV with an Antenna. Half of the channels wouldn't work since the transmitters were on the WTC. It was shocking then, but I didn't really know the impact of it.
A few hours ago, I stopped by the WTC memorial. It felt very somber. I've seen the memorial before, but not on 9/11. There was a flower on each engraved name surrounding the former location of the towers. However I saw 2 of them had Lollipops. I looked closer and saw a note saying that these were the names of two children who died. Very Sad.