I'm flabbergasted that a passing motorist continued driving by. If there is any truth to the facts (a) she was walking, and (b) on fire, then that person is a cold-blooded (I can't print word).
As an aside...the "first responder" and "the fire department" IMO are two separate entities. In my community, a first responder would be a single individual in a 4x4, emergency-equipped, SUV; a fire department would be much more....trucks, hoses, ladders, men etc.
It has been stated that the first responder was at a nearby location. On Hwy 51, I imagine he may have been able to exceed the speed limit due to a fair degree of familiarity with terrain. I seem to recall seeing 8:13pm posted as the time of the 911 call, and 8:15pm posted as the arrival of the first responder. But before you accept those times, please try to find a more accurate account than my recollection.