If they refuse to let go of each other and the fight is indoors and you are the only person available one way is to firmly grab the hind end (not near the front or you will be more likely to get bitten) of one dog and back through a doorway. As soon as the dog's noses are even with the door frame close the door so they are forced apart with one dog on each side. This can also work if the dogs are outside but near a door of the house.
Grab the dog who is doing the most attacking and grab their hind legs and pull them back, usually they will stop attacking. If there are 2 of you each of you grab a different dogs hind legs and pull them apart, do not let go until you have them separated by a physical barrier.
Thank goodness we were outside because our incident occureed out of nowhere. The only thing that worked for me was getting the water hose and spraying both of the fighting dogs and I was able to remove one of them from the kennel area and then I proceeded to get extrememly sick because my adrenalin was pumping so fast. This can be very scary, especially if you aren't expecting it and alone. It was a first time for me, but at least I know what to do in the future, should it ever happen again.
Read Mr. LBNiel-down the list here and check out his blog about losing his pinkie finger. Scroll down in his topic about dog related injuries to find the link. This man should be published. His blogs are so well written and funny.
Outside of a dog, a book is man's best friend. Inside of a dog it's too dark to read!! Groucho Marx