I have seen one in my travels to date. A young one, light brown in colour. Looked about the size between a small and medium dog. Snow in a small opening of field between two stands of bush was about a foot deep and we saw each other about the same time. I was working. It took off through that snow so fast it was like watching a railway plow, there was a snow wake blowing off of its body. I never saw anything that size move so fast. It was awe inspiring. Thats the only one I have seen but I have seen in the same area what I first thought were deer trails and large areas of scraped field. At closer inspection it was pig tracks and the number and sizes indicated what Remlytr has in his photos. A herd or herds!! I know of one fellow here who took 4-250 pounders during the muzzleloader Mulie season in 2014 in that same general area. They are out there, don't kid yourself.
And if you don't think they can be dangerous or deadly you should watch a few European Boar attacks on youtube!!