The boy was shot in the head on Oct. 31, as he stood in the backyard of his South Los Angeles home in the 1000 block of East 84th Street.
The boy's uncle and grandfather were also wounded in the shooting.
Tips from residents led to the arrests of two men. Marcus Denson, 18, was arrested Thursday on suspicion of murder and Leonard Hall Jr., 21, was arrested early Friday morning.
Investigators said the suspects mistakenly thought the victims were members of a rival gang.
"It's our children who are killing our children, so we as parents need to get our stuff together because it is our children, our nieces our nephews, and we need to embrace them and give them guidance and give them love," said Deniece Williams, a South L.A. resident.
Organizers called on parents to take responsibility for steering their children away from gangs to stop the violence.