The side panel on this fire service emergency ambulance identifies all four organizations which together provide EMS coverage and response in Saarbruecken. It is very common for different agencies to work together like this. Some cities rely very heavily on the fire service, while in a small number of situations the fire service does not have any medical units at all. The reasons for this variety of setups seems to be largely historical, and is quite similar here in the USA. Just as here, German volunteer fire companies are usually organized completely separately from EMS providers, although there are a few exceptions too.
Added by Rob Johnson on 09 November 2021.