Agressive briard and his irresponsible and rude owner

This morning Igor was attacked by a big black briard. We saw this dog in a park earlier. There were no friendly feelings when Igor and briard passed each other but both were always on a leash.
This morning Igor was sniffing and playing with a lovely lab - Kelly. Suddenly as a rocket briard jumped on Igor and bite Igor's neck. Briard was not on the leash. Fortunately Igor was. The leash is only 1.5 m long so I started to hit briard immediately. Than the owner came and tried to put briard on the leash. Briard did not let Igor from his jaws. I screamed and started hitting both the owner and the dog. Kelly's owner Julie had some plastic stick. I used it to hit briard and owner. Julie joined me in beating the dog as well. One man who passed by joined too. Igor was crying. I was screaming. Julie shouting. Few other dog owners joined in. I thought Igor's lost. I continued to hit briard. At one point briard let Igor go. Igor was in my hands. He was hurt and in shock just as I was. I checked him and started to comfort him. Fortunately he did not look seriously hurt. The owner of briard just took off. Did not said sorry or anything else. Other dog owners than told me this is not the first time briard attached someone in the park. He attacked a mops and a dachshund recently. The owner was warned but he still does not put his dog on a leash.

Vet said Igor is OK. Apparently briard is an old dog so he lost his sharp bite. Or he lost some teeth when biting mops and dachshund. But if he was younger and with sharper teeth Igor would be in much state.
Both Igor and I were lucky today - but what a morning.

PS. During the evening walk I found out the name of briard is "Chief". His owner never has him on the leash.One of dog ladies told me someone talked to the owner and asked him not to come to the park if Chief is not on a leash. Let's see if that will work but I find such this very supportive.