I'd speculate: Gathering the other passengers' luggage and belongings, identifying the other passengers on the plane, arranging for transportation, arranging fo

I'd speculate: Gathering the other passengers' luggage and belongings, identifying the other passengers on the plane, arranging for transportation, arranging for screening at the other location, in-depth searches of their luggage and other belongings at that location, getting them back to the airport, setting up another flight to their destination (the plane might have left to ensure that it reached later flight connections that it was scheduled for). Separately, clearing the "danger zone", setting up security to keep people away, calling in the bomb unit, use of extraordinary care in testing the device, and so on. But those things sound obvious to me, so maybe you were thinking of something else?