The latest that I read on a update is that it was a family of 4 grizzly bears. A sow and her 3 cubs. They caught her and two of the cubs on Thursday and caught another one today on Friday. Now they are running DNA test to see if they were the bears that did the deed.
I was lucky enough to be driving across the beartooth highway the day after the attacks happened. All of the campgrounds in the immediate area were closed and I saw a lot of activity by the DOW in the area. From what I heard from the locals and the 2 rangers I managed to speak to, the attack started with an overzealous cub. I was told that the campers had followed all the precautions for bear (storing food properly, no food in the tents, etc) but I suspect that one of the campers missed one important aspect of bear safety...their clothing. Cooking attaches odors to your clothes, which can draw a bear's curiosity just as much as actual food. When in areas that have bear, keep all of your clothing (other than sleepwear) in weather proof bags outside of your tent and preferably at least a few yards away from it. Many people dont think about this little point.
I did see two other bears in the area as I hiked and drove the area that day. Both were small, but certainly over a year old.
On a side note, the beartooth highway (which leads from NE Yellowstone through Cooke City and the area where the attacks happened) is a really beautiful area. Well worth the time to spend exploring for a few days. I saw around 30 mountain goats laying in the snow at the top of the pass as well as several deer.
When placing a trail camera don't just look for a well used trail. What you want to do is look for a freshly used trail off by itself that goes from a north facing ridge, thick forest, brushy knob or some other similar bedding area to a food source. Don't forget water sources. Especially in the summer months the deer need water so look for a good trail going down too a creek surrounded by thick cover and place the camera 100 yards up from the water source.
Scent control is very important...