What should I do a dog escaped from a gate?

I was walking my dog and a big mastiff was barking at us and made it through the gate and came towards us. I luckily told him off and he went away. What should I do? I told a neighbor and she to stay away because it bites. What can i do, i do not know anybody here and I do not want to go near the neigborhood with this visciouss dog out. Perhaps now he is back inside.