It happened around 11:45 p.m. at the 76 gas station near Whittier and Rosemead boulevards. This marks the second deadly shooting at a gas station in Pico Rivera in the last three days.
Eyewitness News learned the teen was waiting for a family member who works in the area.
The Los Angeles County Sheriff's Department did not release many details, but confirmed the victim died at the scene.
In an interview with ABC7, a woman named Christine, who said she knows the victim's mother, reacted to the fatal shooting.
"We thought our city was improving but I guess not, because they're coming around doing this," said Christine, who declined to give her last name. "He was a little boy. He was big but he was young. What could he have done to them, to provoke them to come and do something stupid like this?"
Meanwhile, a man was shot and killed on Thursday at a Shell gas station on Washington and Passons boulevards, just a few miles down from Saturday's shooting.
It's unclear if the shootings are connected and there's no information on a suspect or suspects.
Both incidents remain under investigation.