The incident happened near the intersection of Persia Avenue and Madrid Street in the city's Excelsior District. Police say that's where two groups of people had some kind of altercation around 1:30 a.m. on Thursday.
The altercation ended with the unidentified 14-year-old boy being rushed to a hospital with stab wounds. He was pronounced dead a short time later.
Police have not given any motive and do not yet have a suspect description.