The incident occurred about 3:47 a.m. in the 38500 block of 10th Street East, the Los Angeles County Sheriff's Department said in a statement.
Deputies at the scene said they initially responded to a report of loud music at a party. As they were conducting an investigation, one of the deputies was allegedly bitten by a pit bull. The deputy was not seriously injured.
The dog was restrained by a person at the scene, but as the investigation continued, the animal got loose again and charged at the deputies, authorities said. The deputies then opened fire on the pit bull.
Amid the shooting, a friend of the dog's owner allegedly raced around a corner in an effort to apprehend the animal. Caught in the crossfire, the teen was struck at least once in the upper torso, sheriff's deputies said.
He was transported to a hospital, where he was pronounced dead. His name was not immediately released.
Homicide Bureau detectives responded to the scene, where a section of 10th Street was closed.
Anyone with information about the incident is asked to call the sheriff's department at (323) 890-5500.