Very difficult situation. He probably panicked and hoped that by rolling up the window the bad guys would go on to another car - which the bad guys would probably normally do. But these bad guys are most likely experienced in shooting people since the shooter didn't hesitate to shoot at the driver. They probably wanted the vehicle to use as a getaway vehicle or use in a drive by.
Now, if Dike had a CHP and was able to shoot the gunman, then it would be a good shoot. You have a man pointing a gun at you are in imminent danger while you are exposed and nowhere to go.
Its getting bad out there. You're not even safe in your vehicle in line to go through the drive through.