Dubula, whose name means "shoot" in Xhosa, said journalists had shown her a video of her son's shooting, which happened as he hid behind an overturned table with two women in the middle of the street.
In the footage, Ona staggers to the roadside after being shot and a police officer approaches him, screaming: "What are you doing here?" before grabbing his arm and bellowing to fellow officers to "take down the barricade".
After the officer lets him go the boy falls to his knees. He struggles to get up, stumbles and falls again, spitting blood.
An unknown man demands: "Is anyone helping this guy?" as police file past. "Jesus Christ, he needs medical attention.
"Where the f*** are the paramedics, guys? Are you out of your f***ing minds?" someone else screams at the police. Seconds before the footage ends, a man kneels beside Ona and puts his arm around his shoulders.