. . . quickly abandoned, that is.

The method of transport would have been designed to open from the inside, or these would have to be:

1. refugees desperate to be away from their ravage homelands
2. idiots (which might be translatable to fanatics)

They would be abandoned at the shipping yard, and as quickly and quietly as possible, likely in the dark of night. Items would be left behind, either intentionally as too much to carry, or accidentally as an oversight (possibly transportation documents of some kind, forged visas, IDs...). There would be markings in the container that would tell you where they slept, which would indicate a likely number of individuals.

Dan