When expressing intense anger, there are plenty of synonyms to choose from that can convey the emotion just as strongly as "were furious." Some common alternatives could include "seething" or "incensed," both of which suggest boiling rage. "Enraged" or "outraged" are similarly furious, each implying a deep sense of offense or injustice. For a more explosive option, "livid" imparts a sense of red-hot rage, while "apoplectic" may evoke a more physical reaction to the anger. Ultimately, the choice of a synonym for "were furious" will depend on the context and tone of your writing, but all of these options capture a powerful, fiery reaction to a situation.