The number of hijackers specifically related to the Twin Towers
is believed to be ten. The overall number of hijackers on 9/11 is
thought to be nineteen.
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19. There was originally 20 Hijackers, 5 for each plane, but one
of the Hijackers go Flight 93 was arrested on August 16, 2001
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there were 19 hijackers involved in 9/11 and they hijacked 4
planes ......