Short, limited spaces? Here are a few settings that you could base a scenario on:

Miners trapped in a mine.
Promgoers in a limousine, unexpected traffic.
Con-goers in line to see a guest of honor.
Kitchen staff at a restaurant.
Actors at a rehearsal.
Jury in deliberation (this one has been done before)
Native Americans in a sweat lodge.
Exotic creatures trapped in a giant peach. Nah, ridiculous.
Aboard Air Force One.
etc.

Any environment where people cannot, or overwhelmingly will not depart should give you the needed confinement. Situations where people cannot leave limit the environmental interactability though.