This is the first picture that I have ever seen with a Federal Model Y siren mounted on it. I also find it interesting that there are no police, or at least police in uniform, on the scene.
Who knows, they're probably directing traffic. These photos were made from negatives I purchased that are from a newspaper in southeast Kansas (I assume Parsons) over the years. Law enforcement personnel are seen in many of the accident pictures.
It appears that the warning devices on the Dodge were moved over from the car it likely replaced, a 1948-ish Chrysler sedan ambulance:
(SL collection)