I came up out of the subway at Chambers Street (4 blocks from WTC), when the second plane hit. I looked straight up at the towers and saw the two gaping, flaming holes. I went to my office to get my co-workers out. When we were about to leave the building, we heard the rumbling/sucking sound of the first tower crumbling. It's a sound I had never heard before! We headed north. Luckily, we headed north before the plumes of smoke and concrete reached us.