BOSTON -- A teenager was stabbed Monday outside Somerville High School after school let out, police said.

The 16-year-old suffered non-life-threatening injuries when he was stabbed in the chest after a fight on school property shortly before 3 p.m., police said.

Niall Vallega, 19, of Somerville, was arrested and charged with one count of assault and battery with a dangerous weapon and armed assault with intent to murder. A second suspect, Alieu Joof, 19, of Somerville, was charged with being an accessory after the fact.

Police are also seeking a third person in connection with the incident. Anyone with information is asked to call Somerville police detectives at 617-625-1212.

Officials said that the victim and suspects are known to each other and that it was not a random act.

NewsCenter 5 and TheBostonChannel.com will have more information when it becomes available.