The rounds used in this case should be the 155 mm WP (white phosphorus) which is not forbidden by international treaties if used with a PD (point detonating fuze). However if it is used with a VT (variable time) fuze for a high burst effect, then it is aimed at inflicting direct burns to the people under its umbrella, and that is where the dispute lies on the legal level.
I think the case erupted not so long ago with the US or UK forces in Iraq. I did not follow up its conclusion.
Far from the reach of 155 mm, the pictures you've seen may have resulted from the shock wave of a powerful burst of air bombs, high pressure plus high tempreature, and the debris projected by the burst. A lab examination of the corpses may give a clear indication of any forbidden substance.