The victim, a 19-year-old man, was standing near Haight and Stanyan streets at about 6:10 p.m. when another man came up behind him and stabbed him twice, Officer Albie Esparza said.
The victim suffered injuries that were not life-threatening, and the suspect fled on foot, Esparza said. The motive for the attack is unknown.
On Wednesday, officers arrested Nicholas Berner, who has no fixed address and hails from New York, Esparza said.
Berner was booked into jail on suspicion of assault with a deadly weapon, he said.
Ari Burack, Bay City News