The incident happened around 8:20 a.m. in the 13600 block of Bellflower Boulevard, according to the Los Angeles County Sheriff's Department.
According to LASD Lt. Hugo Reynaga, the victim, who has not been identified, was found shot inside a white Audi that had been reported stolen in Lynwood. A woman was found sitting in the passenger seat but she was not injured, Reynaga said.
At the time of the incident, a Pop Warner football game was underway in the high school stadium, adjacent to the parking lot where the shooting occurred.
There were also soccer matches slated for the day.
"We were on the field, warming up, and we heard some shots, we got the kids to safety," said Michael Brown, who coaches a North Long Beach Panthers Pop Warner team. "Came out, found out somebody got shot in the parking lot."
Investigators said the victim was there to attend his son's game. The child, who is reportedly 8 years old, wasn't with his father at the time of the shooting.
"There were people in the parking lot when this occurred, nobody else was injured other than the victim that was seated in the driver's seat of the white sedan," said Reynaga.
Authorities did not provide a suspect description, but witnesses reported seeing the suspect vehicle, a white sedan, fleeing southbound on Bellflower Boulevard from the parking lot.
"We're looking for the driver and the passenger in that suspect vehicle that fled the scene," said Reynaga. "From what was relayed to us was that the driver was not the shooter but was obviously driving the vehicle."
It's unclear if the shooting was a targeted attack. Reynaga said investigators are reviewing surveillance video from the parking lot.
"It's unusual, really, on a Saturday morning at a Pop Warner game," said Reynaga. "We don't know what the motive is and that's what the investigators are working to find out."
Some soccer games were canceled, but the Pop Warner football games continued, even for the victim's son.
"The kid did finish the football game ... I guess the mother didn't want to give him all that information," said Brown. "He's 8 years old, he's still a kid, but later on, I'll check in on them to see how they're doing."
"It brought a tear to my eye because I coach in the inner city, and it's another kid growing up in the inner city without a dad."
Anyone with information is urged to call the sheriff's Homicide Bureau at 323-890-5500.