I understand from reading AAR material on the Centcom site that an RPG launcher was located among the KIAs by the ground troops that responded.

There were at least two AK series weapons and an RPG launcher within the group as they were walking across the road. These are clearly visible in the 38 minute youtube footage if you watch it in full screen mode. The reporter's camera equipment is visible as well.

If you go to the Centcom FOI site there are still images from the same TADS imagery which clearly show these weapons. That makes a minimum of five (including the two stringers and their misidentified bazooka DSLRs) "armed" men out of the group of eight who were engaged by the initial bursts.

Where do you draw the line? Three men appeared to be unarmed but the rest of the group appeared to be armed. At that time, a US vehicle patrol was around 100m away from that location. From the helos it would have looked like a bunch of JAM organising an ambush.

There is quite a bit of speculation that the armed men might have been some sort of security detail for the Reuters employees, but why would local security have an RPG launcher?

There are also reports that the two stringers were in the area on an unrelated job and heard sounds of a contact nearby and went to investigate, which is why they were milling around with the group out in the open with their cameras slung.