The attack was reported at about 2 p.m. in the 2400 block of Taraval Street, where the 39-year-old victim was struck multiple times in the head and arms, according to police.
The suspect, a man believed to be around 40 years old, fled after the attack and had not been found as of this morning, police said.
The victim was taken to the hospital to be treated for life-threatening injuries, according to police.
Anyone with information about the attack is asked to call the Police Department's anonymous tip line at (415) 575-4444 or send a tip by text message to TIP411.
