Dog got loose, what would you do in this situation?

Sorry if this is a log story, but this morning I was taking my 12 week lab for a really short walk, like just outside my house. Out of no where i hear a loud commotion and looked behind to see what seemed to be a rotweiler mix that was fully grown and had a collar on. He was either let out by the owner or probably got out of the backyard somehow (I think he jumped over the fence somehow because i heard some noise from that area). I immediately picked up my puppy in fear that he was going to be attacked because I always hear stories about dogs attacking each other. I hid behind a car and hoped the dog didn't see us, but soon saw that he was running toward us. I calmly walked the opposite direction of the car to try and trick the other dog but realized he turned around and was running straight for us, so I panicked and ran because I didn't know what else to do. I lost my balance while running because I was holding my puppy and messed up my leg pretty bad aswell as my hands and then frantically rang the doorbell of a nearby neighbor but no one was home. Then i turned around and saw my dog and the other dog staring at each other and my puppy was barking at him. It looked like it was going to be aggressive so i started yelling and I guess the other dog got scared because of the barking and yelling. After it backed off I picked up my puppy and ran into my house. I had to quickly bandage up my cuts from the fall because I had to rush to school. What would you guys do in this situation, I was for sure that the situation could've gotten a lot worse.