Help Dog Fight!

Anyone who can help!! I don't know what's up with my dogs! I woke up this morning to a dog fight under the porch. Trixie (female rat terrier) had run Little Bit (female 1/2 border collie, 1/2 blue heeler) up under the porch and wouldn't let her out. We just got Trixie a couple of months ago and I love her dearly but is she supposed to be so aggressive with the other dogs? Dogs must have a pecking order like chickens or something. We had Little Bit first and she was always real timid, about a month ago my father-n-law brought us two pure bred rat terrier's Trixie and Spot (male), Trixie was definately in charge of Spot when she got here. I think she's his aunt if I understood correctly. Anyway, she has been playing mother to all the dogs and I've seen her run Little Bit under the porch before, usually for doing something Trixie didn't want her doing. One time I went out late in the night (midnight or later) and gave them a couple of treats off the porch before going to bed and Trixie wouldn't let Little Bit near me, she was being protective I thought. I coaxed her out of that. But now don't know what to do, if anything. Trixie is great with my son, she even lets him take food out of her mouth!! I really like her but she was so aggressive this morning it scarred me. I have never really had dogs myself, my family does but they're inside pets. She wouldn't lay off Trixie even when my DH came out of the house and tried to get her out from under the porch. We didn't see what started it but both dogs are tore up and Little Bit is hiding under the neighbor's trailer and won't come out. Trixie did come to me after she calmed down and we chained her until we can figure out what to do. What scared me the most was that I thought Trixie should have quit when I called her and she didn't. My DH says that it is unreasonable for me to expect her to stop the adrenaline rush from the fight and come to me. But he even fired his gun in the air to break it up with no result. I poured some water over them from a pot on the porch, I had to pour it between the porch slats, so it wasn't very effective Little Bit managed to get out from under the porch and run to the neighbors before I could get back with the hose. DH had to stop Trixie from going after her still. He managed to get to the space in the fence before Trixie, pure luck he was already there when Little Bit streaked past. She didn't go for DH but she wouldn't come to me until she calmed down and then DH acted like he was scarred for me to get close to her until she calmed down. She came up to me and I put her on a leash and he took her out and chained her. Any ideas? Should I be worried about having her around my son he's only 2. I'm very upset about this, Dh says it's normal for dogs to fight. What to do? What to do?