I am going to drop this here before I head to the woods.  I always try to empathize.  

I am trying to think of what i would have done as an officer in that situation. I am one of the first in the pursuit.  The UPS vehicle gets jammed up and stops. I get out of my cruiser (or do I) then close the distance. As I do hostile fire erupts from the truck where the hostage is being held.

Is the shooting coming from the truck a threat to the motorists? If I don't act will innocent lives be lost? Do I dive behind an innocent person's car for cover and possible place them at risk of any fire I draw? Do I stand in the open and engage the shooter? Will my instinct to seek cover under fire even allow me to do that? Do I run back to my cruiser? Is there any action I can take that won't have potentially disastrous consequences? If in the split seconds I had to make the decision, I chose the best one, would I be able to execute it properly under intense stress?