The stabbing was reported at about 11:30 a.m. Saturday in the 200 block of McAllister Street.
Two men, ages 26 and 32, approached the other man and started a conversation that escalated into a fight, police said.
During the fight, the suspect, a 45-year-old man, stabbed the other two men several times.
They were taken to San Francisco General Hospital, police Officer Albie Esparza said.
The suspect was arrested a short time later, police said.
Dan McMenamin, Bay City News