The question is: possible that UN's staff does not denounce these obvious infractions to of the recognized war rules?
It could be objected that it is guerrilla and not war, then if it is guerrilla all it can be admitted, comprised the irregular use of aid (ambulance and hospitals) is not astonished to us if  the civilians used as shields comes hit, the guilt falls back on who puts them in danger not certainly on who hits without wanting it.
Perhaps better to remember that the Convention of Geneva recites exactly thus:

"The ambulances and the military hospitals will be recognized neutral, and, like such, protect and respected from the belligerents, during all the time in which they will have sick and wounded people inside of them. The neutrality will be suspended if these ambulances or these hospitals will be safeguarded from a military force ."