Police spokesman Officer Albie Esparza said the 52-year-old man was hospitalized with life-threatening injuries after falling and hitting his head on the ground during a fight with a motorist at 18th and Missouri streets.
According to police, the man was walking in a crosswalk at the intersection at about 10:45 p.m. when another man driving a two-door white car turned into the roadway and nearly struck him.
There were multiple witnesses, who reported the two men began yelling at each other and then started to fight, police said. The driver then struck the victim and the man fell to the ground.
One witness reported hearing a sound like a baseball bat striking the victim, but no weapon was seen, Esparza said.
The driver, described as a white or Hispanic man between 25 and 40 years of age wearing a flannel shirt and jeans, then drove off.
Witnesses described the car as possibly a Geo or an Acura Integra with a license plate that begins 5XM or 5SM, police said.
Anyone with information can call the Police Department's anonymous tip line at (415) 575-444 or text TIP411, or call Bayview station at (415) 671-2300.