Ask your local police department what their views are on the subject.
Police vehicles (except for those used for community services) are beefed up to handle the extra electrical loads. (heavy duty alternators, dual batteries, etc)
EMS personnel should be able to advise you as well.
Who would know better than the people who have tried them or actually use hybrids for emergency use?
You would think the engineers would, but that doesn’t always hold true as everyone has different uses and circumstances.