2001.....:american airlines flight 11 ,united airlines flight 175, american airline sflight 77, united airlines flight 93 were hijacked on the morning of September 11 by al-qeada affiliatedislamic extreamic Two planes were deliberately crashed into the twin towers of the World Trade Center, one was crashed into the Pentagon and one crashed into a field in Pennsylvania. Both towers of The World Trade Center collapsed; in total 2,976 victims and 19 hijackers were killed and over 6000 people were injure