Sandoval had been visiting family and was waiting for someone to pick him up. Investigators think he may have known his attackers.
His relatives are in disbelief.
"His mom's just crying; devastated, of course," said Felipe Aguilera, Sandoval's cousin. "His sister, she was here whenever that happened, but I think she was asleep when they called her."
Police interviewed several witnesses, but they weren't able to get a good description of the getaway vehicle.