I'm not comfortable with an unleashed dog and now I'm yelling at the owner
Why would you yell at the owner of the dog?
The owner did not make sure the dog is safe.
It's understandable to react this way. Dog owners are supposed to make sure their pets don't menace other people, yet this owner didn't make sure of that.
I'm going to get the cops and create a huge deal out of this.
That's fine, if you truly feel unsafe then you can deal with it whichever way that you deem fit. However, I would stop yelling at the owner and let the police handle it now that you've called them-- that's the more mature thing to do.