Jumping on this as one who was a ff/pm and officer and is a product manager: break things down into smaller and smaller problems, prioritize and resource manage. Show up at an MVA, it's a series of questions: how many patients do I have? how acute are they? what resources do I have coming or need? traffic control? tow? more patient transport? what do we need to make each hit a success point - do I need to take the door or roof off of this car to get the patient out? stabilize that vehicle to make it safe for us?

As you slice and dice, the problems become simpler, the answers easier, and the insurmountable chaos you showed up to becomes progressively more manageable.