Yes, got real quiet in NYC that day. No honking horns, no yelling in the street, empty restaurants, stunned wait staff milling around, not much traffic, empty cabs. Real quiet real fast. Engine company 54 took off and headed downtown, some of whom never returned.
Our neighbor across the hall was in the 2nd tower when it got hit. He made it out just before it collapsed. Hid under a parked car when the tower came down. Walked the 2 miles or so home. Covered with at least a 1/4 inch of soot/ash when he got here. Sat down on our couch and tried to compose himself. Did not want to be alone in his apartment.
Awful, awful day.