gramatická analýza: Raněná byla odvezena do nemocnice.
Past Passive Participle long form odvezený from odvézt. Raněná is also a PPP long form from ranit.
The main verb (the conjugated verb) is byla; the subject must be feminine singular. The only possible feminine-looking subject is raněná (with the implicit noun žena), the injured woman.
The people who carried the injured is not explicitly reported here. The default subject would be "they". Try paraphrasing the sentence as: "They carried off the injured (woman) to the hospital."