Which scenario indicates an officer is involved in a gun battle?

The scenario that indicates an officer is involved in a gun battle is one where the officer is explicitly described as being engaged in such an encounter. This option directly states that the officer is involved in a gun battle, making it clear and unambiguous. In law enforcement, a gun battle refers to an active exchange of gunfire between officers and suspects, which is a critical situation requiring immediate response and tactical considerations.

In the context of the other options, while they may imply a critical situation, they do not explicitly confirm that a gun battle is occurring. For example, a disabled vehicle could indicate distress or a need for assistance but does not indicate a gun battle specifically. Active shots fired reported indicates there may be gunfire in the area, but it does not confirm the officer's involvement. A request for medical assistance could be related to an injury sustained in a shooting but does not confirm that the officer is currently engaged in a gun battle. Therefore, the clarity and definitiveness of the statement regarding the officer's involvement in a gun battle make it the correct choice.