I had started my first year of secondary school only a little more than a week before 9/11. The attacks happened in the early afternoon Western European time, so I was at school when it happened and unaware until later. I actually first heard about the attacks from my father in the car when he picked us up from the bus stop, although he didn't really communicate just how bad it was, or didn't yet know at the time. Soon thereafter at home I first saw and was shocked by the infamous footage of the Twin Towers, I seem to remember I saw the towers collapse more or less live on tv. I remember thinking, although I was an 11, almost 12-year old with pretty little understanding of the world back then, that this would change things majorly and that things would not be the same after this.
Unfortunately in the first couple of years of 9/11, being darker-haired and darker-skinned than the average Belgian teen and being the most foreign-looking kid (despite not being a foreigner, though I do have some Mediterranean blood), at least in my relatively rural region, I was subjected to quite a lot of racist bullying at school, starting the long misery that were my secondary school years for me.
To those who may have been personally affected by 9/11 or any other terrorist attack, I offer you my most sincere sympathy.