And wsj.com: http://online.wsj.com/article/SB10001424052702304364904575166611840931060.html?mod=WSJ_hpp_sections_news
According to U.S. officials, the pilots arrived at the scene to find a group of men approaching the fight with what looked to be AK-47s slung over their shoulders and at least one rocket-propelled grenade.
A military investigation later concluded that what was thought to be an RPG was really a long-range photography lens; likewise, the camera looked like an AK-47.