A few minutes after boarding had been completed for my Shenzhen Airlines flight in Guangzhou, I noticed a man run down the aisle towards Business Class, with FAs following close behind.

I didn't see either of them get removed from the plane, but an announcement asking everyone to disembark with their carry-ons was made soon thereafter. We did, and surprisingly, we waited only about ten minutes until we could board again. Naturally, that incident (?) caused us to lose our slot - not that I expected us to take off on-time anyway - so another half hour was exhausted before finally leaving the gate.

Still, what could have happened?