Daredevil
It was a B-25 and it occurred on 28 July 1945. While no 9/11 (and it was an accident due to fog), it was no small event. An engine went right through the building and landed on the street the other side killing passers-by. In all 'only' 14 were killed, but it was a Saturday.
http://history1900s.about.com/librar...mpirecrash.htm