The passenger brought the discovery to the attention of a flight attendant, who then called security ... Paris tells TMZ. We're told all of the passengers were ordered to deplane.
Security is now doing a sweep of the plane, looking for other weapons. Paris was on the plane with boyfriend Cy Waits in first class, of course. The video above was taken as Paris arrived at LAX this AM.
UPDATE 9:00 AM PST: The plane has now been swept, and we're told passengers are in the lounge waiting to get back on.
UPDATE 9:39 AM PST: Law enforcement sources tell TMZ .. the blade is a "box-cutting knife" which belongs to the airline crew.
We're also told police were not called because airline officials knew who the knife belonged to.