Napa Police were called following a reported assault on First Street in front of the Archer Napa hotel Sunday night.
A San Francisco woman reportedly knocked out her boyfriend shortly before midnight, then rode with him in the ambulance to Queen of the Valley Medical Center where he went for treatment, police said.
At the hospital, the woman, Catherine Nicole Stevenson, 29, refused to stay out of the ER's treatment area and had to be restrained, police said.
In the waiting room, she caused a scene and grabbed two registered nurses and swung at the Fire Department battalion chief, striking him on the arm, police said.
Neither the nurses nor the battalion chief were injured, police said.
Police booked Stevenson, who was described as intoxicated, into the Napa County jail for possible charges of battery.
Police said the victim, who was also intoxicated, was not cooperative.