This is what the UN has to say about it in their basic principles on the use of force and firearms by law enforcement officials (art. 9): "Law enforcement officials shall not use firearms against persons except in self-defence or defence of others against the imminent threat of death or serious injury, to prevent the perpetration of a particularly serious crime involving grave threat to life, to arrest a person presenting such a danger and resisting their authority, or to prevent his or her escape, and only when less extreme means are insufficient to achieve these objectives." I see no grave threat to life here.
Manhunt in Memphis, Tennessee continues after officer, 33, fatally shot (AP)
from the article: Israel to complain to UN over Syria incitement of border violence