As OrigamiPastrami notes there are real accidental deaths in specific freezers.
That said most freezers by law have an internal quick release that should work even if there's a padlock through the secure holes on the outside latch.
It's probable he has barricaded the door with something heavy and told the people inside that the first one out the door will be shot dead.
Quora suggested jamming the extraction fans to stop the freezer working and potentially triggering a service alarm should the quick release not work:
That said most freezers by law have an internal quick release that should work even if there's a padlock through the secure holes on the outside latch.
It's probable he has barricaded the door with something heavy and told the people inside that the first one out the door will be shot dead.
Quora suggested jamming the extraction fans to stop the freezer working and potentially triggering a service alarm should the quick release not work:
https://www.quora.com/What-if-I-accidentally-ended-up-locked...