today i took my bullmastiff and my neighbors blue pit for a walk around the block like any other night. Both of these dogs are around 11 months old so they are quite playfull, the pitbull more than the bullmastiff. Down my street two small dogs were out on the street barking at my dogs, the pit wanted to go after them all the time so on the way back i decided to take another street home that i usually i dont take. I was walking the dogs down this street with no problem until i heard this dog barking in a back yard. I paid no attention and kept walking, i then this full grown pit jumps this fence and starts heading towards us. I knew that this wasnt going to be good, i just had a feeling. This pit walked up to us not really agressive but my dogs were not to sure about this dog. My two dogs and this pit stood around for like a minute without anything happening. This pit looked like if he wanted to get near me because he was going around my dogs towards me. As soon as this pit got about a foot distance from me, my bullmastiff attacked like i have never seen my bullmastiff before. I tried to keep them appart but it was to risky my neighbors blue pit then started to attack the other pit aswell. I had three dogs in attact mode around me. I honestly feared than my bullmastiff was going to get seriously hurt and there was nothing i could do to stop it. That wasnt the case my bullmastiff fought until he put the pit on the ground while holding him with his mouth on the dogs neck. The pits owner finally showed up and took his dog. I have never exposed my dog to any kind of violence but today he and my neighbors dog protected me from any injuries. My dog is usually laid back, calm, and good with people even kids. When he attacked the pit it was really sudden, no bark, no signs, should I be concern or did he just attack because I was in danger?