Checked with the office, and yes, it was one of our planes.
The problem was that the pax weren't allowed to carry all their bags onto the plane - you, the usual 20 litres of zam-zam water, etc - so they were told it was being loaded downstairs.
All the pax got their seats well before the freight had being finished being loaded, so to help keep the cabin cool all the doors were shut.
Some of the pax saw their bags sitting outside, and decided that they weren't going to leave without them, so one got up and before anyone could stop him, went up to the door and opened it. A whole bunch of pax then started to follow him out the door, and away they went!
The end result was that the flight got cancelled, but fortunately no-one was hurt at all.