Two construction workers were stabbed around 2:00 p.m. near Geary and Larkin Streets, according to the San Francisco Police Department.
The altercation began when a man SFPD described as homeless urinated at a construction site.
When two construction workers asked him to stop, the suspect pulled out a knife and stabbed both workers. One victim was seriously injured and transported to SF General Hospital.
The suspect was located and arrested by SFPD.