I was a employee of Morgan Stanley and was just getting off the elevator of 2 WTC on the 62nd floor when the plane hit 1 WTC. Apparently a ball of fire wrapped around our building and my colleagues all ran for the fire exit, which happened to be across the hall from the elevator bank.
I joined them running down the stairs, immediately sensing something was terribly wrong. When I had reached the 10th floor there was an announcement to return to our offices as there was a fire in 1 WTC, but since I was so far down I would have to go to the first floor to get on the elevator back up.
When I got to the ground I was on the plaza level one floor above the street. I stood in shock for I don't know how long. It looked like a war zone outside the building -- cars on fire, pieces of airplane (engines, wing, etc) and a glittery rain of debris and on the plaza unfortunately I realized I saw people hitting the ground who had jumped from above, which to this day torments me.
I snapped out of the daze and realized I needed to get out. I ran down to the mall under the Trade Center. Suddenly everyone was knocked down by a huge bang and the feeling of an earthquake, which I assume was the second plane hitting my office. I ran for the arch of a store front as it felt as if everything would collapse then. Once I felt safe it didn't, I started for the subway. Luckly I found some of my coworkers and we all went at the direction of the Port Authority people down the E train station out the chamber street exit (you couldn't exit the normal doors as debris could kill you).
I remember looking back and seeing both buildings on fire and thinking it was strange as I didn't know a second plane had hit. I read a lot of Tom Clancy type books so once I heard a plane had hit the Pentagon I knew we were under attack. I wanted to get off Manhattan ASAP.
We ran through the streets (like a Godzilla movie) up one of the avenues with thousands of people evacuating to midtown. I stopped to call my parents at some point about a hour after the attack. At the Union Square W hotel I remember someone there said that the Trade Center had collapsed and I think we all almost fainted as we didn't know where so many of our coworkers and friends were.
I met up with my friends and girlfriend and we tried to figure out how to get back home, which was Hoboken at the time. We finally got on a Path train, which was running, surprisingly. I remember I broke down crying thinking about how I didn't know where so many people I knew were and if they were OK. I will never forget looking up and seeing the whole train car crying with me. That's my story.