It started out like any other week-day.  I reached my 15th-floor office in 90 Broad Street at about 8:45.  Shortly after I had settled down, a colleague rushed in to tell me that a plane had crashed into the Twin Towers.  I looked out and saw thick, gray smoke blowing east and emanating somewhere from the north.  There was paper flying high in the air.  Strangely enough, it reminded me of a ticker-tape parade.

I calculated that if the Towers fell, their approximately quarter-mile-height would be insufficient to hit 90 Broad.  I called home to tell my wife, who was on the Island, to witness this incredible event.  At the time, we thought it was a freak accident.

While we were looking at the CNN website, we heard what sounded like thunder and felt our entire building vibrate.  We turned on the radio and our fear that this was a terrorist attack was confirmed when we heard that a second plane had crashed.  At that point, we began to wonder whether it was safer to stay in the building or leave.  We had no clue if the subway was running.  We did not hear any evacuation instructions on radio so I decided to stay put.

When the first building collapsed, we heard a muffled explosion.  We saw a flash of light.  We decided to leave 90 Broad for open space in Battery Park.  I picked up my laptop because I feared that if my building collapsed, all my work would be lost.  We took the elevator down.

As we reached street level, I could see an advancing cloud of debris and dust down the Broad Street canyon.  For a moment I thought the New York Stock Exchange had been bombed.  Two of us started walking towards Battery Park.  We heard a plane that we could not see.  There was dust and smoke everywhere.  We hoped it was a fighter jet enforcing the no-fly zone that we had heard about on the radio rather than another aircraft on a suicide mission.

Debris and dust were hurting our eyes.  I put up my handkerchief to cover my mouth.  People were moving in an orderly way.  I saw some people, covered in dust, coughing and sputtering.  I could see some people crying.  The sirens of passing fire-engines made it impossible to think or talk.

We got onto FDR Drive North.  As we crossed South Street Seaport, there was a second explosion and a massive dust cloud formed to our west.  We figured that the second tower had fallen.  I tried calling home on my cell-phone but it took more than forty-five minutes to get through the first time.

Thousands of people were ahead of us already so we just walked.  At several points we had to cross traffic dividers.  Elderly people were having trouble doing that.  A woman in a wheel-chair had to be lifted and carried across the barrier.  There were police cars, vans and fire trucks heading in the opposite direction at a high speed.  The last thing we wanted was to get hit by a truck.

I decided to walk home directly instead of crossing over on the Brooklyn Bridge with my colleague who lives in Brooklyn.  I headed uptown on Second Avenue, toward the Queensboro Bridge.  I walked for three and a quarter hours to reach Roosevelt Island.  As I carried my computer, it struck me that though heavy, it was lighter than my 30-pound, 2-year old son Dhruv, who was safe on the Island.

I reached home at 1:30 p.m, covered in soot.  I thought: "This is what it must be like in a war zone."