Several years ago, on the news, they were talking about a lady who stopped at some random pasture along the road, to see the new foals. Took her young child, over the fence to go see these horses, and the child was kicked and killed by a protective mother. They blamed the horse. It was horrible the child was killed, but totally preventative. There was a fence there, not only to keep the horses in, but keep other things (people included) out.!
This is a perfect example, of why you don't go up to a strange horse, especially if there are young foal present.