I was in kindergarden. Considering I went to a catholic elementary school, we were made to go to the church and pray (not told why) until we were picked up by our parents.
I remember coming home, and shortly after my dad burst through the door and went straight for the phone, trying to get ahold of my aunt and uncle, one of which worked in the towers and the other being a firefighter for Ladder 25 on 77th. and broadway. Turns out they took the week off to go visit family in Massachusetts.
I went down with my dad a few months later when he was delivering a granite plaque he made to Squad 18, with all the men that died that day. Still hanging up in there now if I'm not mistaken. Depicted from their website: