Janesville police are investigating a shots fired incident.  Police say officers were called to a residence in thee 2300 block of Rockport Road just after 3:00 a.m. Sunday for the complaint.  Officers say a man and woman were arguing in the driveway when a neighbor shouted at the two.  While reporting the incident to 911, police say the man causing the disturbance shot at the caller.  Police say all parties have been identified.  No one was hit by gunfire, but the woman was treated for injuries at the hospital and released.  The suspect was not in custody as of early Monday morning.