In Berlin some stations have also, i.e. ASB Samariter, Johaniter St John or Bundeswehr Ambulances stationed at the FS. Manned by the respective associations' teams. Same in Frankfurt.
Yes, the idea of housing these ( and other ) organizations' ambulances at fire stations is fairly common in Germany. Although not widespread, it also happens in a few locations in the U.K. and here in the States. I remember when I was a student in Heidelberg in the early sixties the fire service was one of only a few full time German brigades which did not run any ambulances, but the German Red Cross took care of that responsibility. It seems to me that the emergency services in Germany - police, fire brigades, THW and the various EMS providers - all work very well together at incidents, which is not always all that much the case in some other places.
Added by Rob Johnson on 04 April 2024.