what more are we learning about them and how this happened? >> reporter: yeah, lindsey, we're filling in this time line that started back when this group of four as you described, lifelong friends left south carolina in that white van with north carolina plates and nen made that road trip hundreds of miles here to south texas to brownsville where according to family members one of the group had a cosmetic procedure scheduled in neighboring matamoros, and they crossed over one of the international bridges here, and federal authorities tell us it was shortly after they crossed that bridge that that white van took a heavy amount of gunfire, a barrage of bullet, according to some of the photos and videos that we've seen that then led to this video being captured showing these gunmen in broad daylight walking very casually i might add with these victims putting them in the back of a pickup truck and