9/11: Flight attendant reports stabbing
9 September 2011 Last updated at 11:31 BST
Audio of Betty Ong, a flight attendant on American Airlines Flight 11, speaking to American Airlines reservations agents.
"Somebody's stabbed in business class, and, um I think there is Mace that we can't breathe," Ms Ong says. "I don't know, I think we're getting hijacked."