Check out this research: https://www.mdpi.com/2571-6255/6/9/331

An explosives safety separation distance, ESSD, from a substance, article, or structure with reacting material, specifically burning material, is one where an individual would not receive second degree burns and would not be exposed to hazardous debris (<79 Joules) at a density greater than one fragment per six hundred square feet

The table below from this site shows an appropriate evacuation distance…

I’d presume the amount of explosive munitions in that burning truck was on the high end…