Dog bite at Macdonald park

Hi, 
last Thursday I was at Macdonald park by the state police barracks when I was bit(unprovoked) from behind by a what looked to be a German Shepard(on a leash) as I walked by it. I didn't know if it was a large scratch or a bite until later.. I have reported it to the local dog officer and urgent care. I just wanted to give a heads up to anyone walking so it doesn't happen to you. The bite is quite large across my thigh. The dog was with 2 young(maybe early 20 yr old guys).the dog was a German Shepard and grey/brown mix if I remember correctly.  So just a heads up!