CamWorld: Thinking Outside the Box 1:39 AM: Reports are saying the hijackers used knives and box-cutters to hijack the four airplanes that ended up being used as giant flying bombs. Apparently, knives up to four inches are allowed to be carried on board. Unsubstantiated reports now say that the hijackers used plastic-handled devices with razor blades stuck in them. They also started killing stewardesses to lure the pilots from the cockpit in order to gain control of the plane. The knives were constructed from pieces hidden in shaving kits.