I was 16 years old and had just arrived in beis medresh in LA a couple weeks earlier.
Was sleeping in the old decrepit YOEC dorm and Rabbi Thaler came running down the halls screaming that the one of the twin towers had been hit.
I think I was the only person back then to have a cell phone (just bought it when I arrived in LA) and I was using the 3 lines of text-only internet on my Motorola Talkabout (a Startac derivative) to get updates. I was also the news guy for yeshiva and I'd keep coming back into the zal and update bochurim and rabbeim as to what was going on. My rebbi pulled me aside to see if I had a TV that I was getting updates from...internet on a phone was pretty much unheard of back then. In fact Sprint was still giving away the 2G internet for free to get people to use it.
The LA cops came to checkin on us a few times that day as well. Until all the planes in the country were grounded there were still rumors of tons of other hijacked planes.
I actually had a ticket to go from LAX-CLE on 09/12 IIRC as CO had strict 30 day max stay then and I had another return ticket for Sukkos and was going to throw away the 09/12 ticket. In the end I was able to use the 09/12 ticket to come home from yeshiva at the end of the year as the flight was cancelled of course.
My father sent me back to yeshiva after sukkos with a kit of cipro and atropine to keep with me in case of anthrax or nerve gas attack
