Translation of inmunizar

A bystander who watched the entire scene all the time decided to help me. He was an older man, around seventy, but nonetheless he went to the oldest of these kids and slapped him. The boy was sixteen.
I bought a bottle of water and took a pause to regain my energy. Not long after that I descended again and looked for a cafe place near the central square. To my surprise I found a very modern place.
The city was incredibly vivid and we were impressed by its size. We walked a lot through all the different neighborhoods, starting with Recoleta, an upper class neighborhood with its famous cemetery.