September 11, 2001: Islamic terrorists crashed two airliners into the World Trade Center in New York, causing the 110-story twin towers to collapse. Another hijacked airliner hit the Pentagon and a fourth crashed in a field in Pennsylvania.
The only plane allowed to fly on 9/11 after the attacks was a plane from San Diego to Miami delivering anti-venom to a man bitten by a highly poisonous snake. It was accompanied by two jet fighters. Sept. 11, 2001: As seen from Brooklyn