Loose pit-bull encounter

Around 12pm today, I was walking downtown at the intersection of 98 ave and 111st, when I spotted a senior looking man who was having a hard time taking his 140lb pit-bull back home from a walk. The pitbull looked like it was more interested in staying outside. It eventually got loose and ran right to me from across the street. It immediately started attempting to bite at my legs completely unprovoked. I stood my ground and kept eye contact and kept facing it as lt tried to circle around me to get me from behind. Eventually it ran off to someone else. Thankfully I managed to stand my ground and wasnt touched. As I was getting out of there It sounded like it may have attacked someone (or someone's dog) behind me because I kept hearing yelping, and a bit of commotion. All the while the owner was slow to keep up to his dog.

I immediately reported this to 311 but haven't heard or seen anything come of this. Im looking for anyone who witnessed this or anyone who has heard about this and has any details of the outcome. This guy lives fairly close to me and I do not believe he is fit to care for this animal.

Edit: 140 may have been an adrenaline powered exaggeration. Lets just go with medium large sized