From what I can see there was two guys carrying something that looked like AK47's, and they were correctly interpreted as AK47's by the US soldiers. But the whole incident seems to have been sparked by them mistakenly spotting cameras as being RPGs, the decision to engage was based on the RPGs (cameras), not the AK47's.
We can criticize them for mistaking cameras for RPGs, but if we imagine for a second that they were in fact RPGs, because that's clearly what the US soldiers thought, the question is was it still wrong by them to engage the group and how they did it.
Assuming their orders were "you can engage any unauthorized groups of people carrying multiple guns as long as collateral damage is kept to a minimum" then I think it was right to engage. Their actions when the van arrives though, that's harder to judge, I'm leaning towards it being wrong to engage the van since they were only gonna pick up wounded.







