I think they used tear gas before they started slashing the crew with the box cutters. If you can't see and you aren't expecting it, they could slash your throat pretty fast. That goes for the crew back with the passengers. However, I would have expected the cockpit crew members to at least put up a bit of a fight.
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"Returning hate for hate multiplies hate, adding deeper darkness to a night already devoid of stars." - Martin Luther King, Jr.