Here are some more photos of the above site. I was told they had not put up the antennas yet. But if they are in a rush, one team may be responsible for the antennas. Typically a site prep crew is responsible for the underground conduit, concrete pad, and cabinet placement, which is what these guys were doing.
Staring from the top, which is T-Mobile:
Middle is Sprint:
IMO the bottom is likely Dish (Boost Mobile, etc):