Mom very clearly didn't have a handle on her child, who was screaming "I hate my mother!" at the top of his lungs and running down the street quite a bit faster than his mother could.
It's difficult to know when intervention would be appreciated or resented, so I asked. "Please!" she gasped. So I ran the child down and blocked him from running any further, until his mother was able to catch up. It wasn't over. Apparently Victor is autistic, and flipped out all over when she tried to get him to go back home with her, punching her in the breast and face until she couldn't keep hold of him any more. He sat on the ground and screamed. The sight of his mother set him off. "I hate my mother! I don't want to see her face for a thousand years!"
Resolution: Get permission to try to help from mom, then get close to the ground. His level. Non-threatening.
"Hi Victor, can I walk you home?"
"I don't wanna see my mother's face."
"Ok. Will you stand up? Then we can walk home."
And as long as she stayed behind us, and he couldn't see her, he was fine. She now has our phone numbers. I hope she doesn't need to use them, but I hope if she does need a hand, she'll call.