More details are supposed to be released in the next couple of days
DEBKAfile has a play-by-play, but of course there may be as much fiction as fact in their report. I do find the idea of Kurdish cooperation in the operation plausible though.
The other plausible idea in the story is that our forces had no idea how many people were holed up in there and what they were packing, hence the overkill in force brought to bear.