Petaluma man Sheldon Berkey, 27, Tuesday remained in the Sonoma County Jail, suspected of assaulting a man with a large wooden walking stick.
Petaluma officers arrested Berkey after several people called from Putnam Plaza downtown at about 12:30 p.m. Monday to report two men fighting.
Witnesses told officers one man had repeatedly hit the other man in the chest with the stick, causing him to fall and hit his head on the concrete, Petaluma Sgt. Marty Frye reported in a release.
The victim, identified only as a 42-year-old Petaluma man, was found unconscious on the ground in the plaza.
Witnesses pointed officers toward the nearby Petaluma River, saying the man with the stick had run that way. Officers found him hiding in bushes, Frye said.
Berkey was arrested on suspicion of assault with a deadly weapon causing great bodily injury. At the time of his arrest he was on probation for a DUI and an obstruction case, according to jail records. His bail was set at $55,000.
Petaluma Lt. Danny Fish Tuesday said the two men, both local transients, know each other well and are known to police.
Neither said much about why they were fighting, Fish said.
The victim was treated for minor injuries and released.