@FBM,
Quote:Maybe "stall" is a typo. I think it should be "staff."
If so, then at least in British English, we would say "Our security staff were fired". In British English, we use plural verbal agreement to emphasize when an entity is made up of a group of people, whether this entity itself is marked as plural or not. This is also true of companies, bands, sports teams etc. E.g. Rolls-Royce are planning a new model of jet engine; Radiohead are playing six concerts this year; Manchester United are doing well this season.
In American English, one would, I believe, say "Our security staff was fired".