is firing from an ambulance a crime against humanity?

I suppose the term “war crimes” is probably applicable only to wars between states, and in that context I’ll bet firing from an ambulance counts as a war crime. In the present Libyan context does it count as a “crime against humanity”? I’m not well-versed in what does count, but the following sort of incident apparently happened many times in Tripoli yesterday, and it’s abominable:

1213: Naser, living in Tripoli, has told the BBC World Service that gunmen in an ambulance were among those who opened fire after Friday prayers. He broke into tears as he related the attack: “And then we saw [an] ambulance coming. We were so happy – at least they’d take these wounded people. When the ambulance stopped, the back door opened. Armed people came out of the ambulance and started shooting at the people. I can’t explain the feeling how it was. I was terrified. I mean, [an] ambulance.”

Here again, it’s something you’d expect only The Joker to come up with.