The incident began about 10 p.m. when two suspects approached a male juvenile near the intersection of East Fifth Street and North Rockvale Avenue and fatally shot him, according to the Los Angeles County Sheriff's Department.
Another person then returned fire at the assailants as they attempted to flee the scene, investigators said. One of those individuals was killed and the other was wounded.
Paramedics transported the injured man to a hospital where he is expected to survive.
The identities of the deceased were not immediately disclosed.
Two firearms were recovered at the scene, the Sheriff's Department said.
A description of the person who shot the two men was not available. The motive for the initial attack is under investigation.
Anyone with information about the shooting is asked to call the sheriff's Homicide Bureau at (323) 890-5500 or Crime Stoppers at (800) 222-8477.