He is charged with murder and attempted murder for the shooting death of his cousin, 8-year-old Jasmine Sanders.
Sanders was struck in the chest by a stray bullet last Wednesday when she was playing outside her apartment building at 76th and San Pedro Streets in South L.A.
The suspect's mother, grandmother and uncle all attended the arraignment, but declined to speak in front of the camera.
Off camera the 13-year-old's mother told Eyewitness News that she and her family are distraught over her son's arrest and over the death of Jasmine.
She says she is very close to Jasmine's family and visits with them frequently, but that her son did not know Jasmine and lived with his grandmother. The suspect's mother also said that she did not know if her son was innocent or guilty.
Police say that the shooting was gang-related and that Jasmine was not the intended target.
The shooting prompted outrage in the neighborhood, with police calling for witnesses to come forward to help them make an arrest.
Tips helped investigators arrest Jasmine's 13-year-old cousin.
Community leaders Wednesday expressed relief about the arrest -- calling it a positive step towards stopping the violence.
"This is something that we are challenging and continuing to challenge the community -- it is your community take it back, get involved, stop gun violence especially teen gun violence," said community activist, Earl Ofari Hutchinson.
"We want our teens to shun gun violence and we want them to shun homicide by gun. That is a message we try to convey to the young kids that are to often the victim and the perpetrator," said community activist, Lita Herron.
The 13-year-old suspect will be back in court on September 8 to enter a plea.