Carmyne Paschall Payton, a sophomore in high school, collapsed while running laps.
Payton's mother, Tiffany Wofford, tells KABC's sister station, WABC-TV, she received a phone call and raced to the school, and she was watching as responders tried to resuscitate her son.
"He never woke up," she said through tears. "He never woke up."
Wofford, still in absolute shock over what happened to her son, said the basketball team was something that had become a recent passion for him.
"And he's like, 'Mom, I made the cut! I'm so excited,'" she said.
She said she initially figured her son had broken a wrist or something, never suspecting it would be so much worse.
"I wasn't going there expecting to see that," she said. "I just want to know what happened. I just want to know if the autopsy can tell me something."
Doctors say about 90% of issues like this in high school sports can be picked up by simple electrocardiograms - but should a basic cardiac exam be required for high school sports?
As for Carmyne, Wofford says he was cleared in August at a basic physical and in good overall health.
Now, the family is dealing with a loss too much to bear. Carmyne has one older brother and three younger sisters.
"Anything I asked, he was like, 'OK mom, OK mom, OK mom,'" Wofford said. "I don't know. I don't know what I'm going to do without him."