Initial reports said the boy was in a hospital in critical condition after the incident involving a 27-year-old man who is now in a relationship with the mother.
Earlier Friday, Peterson was at the Vikings' practice facility and requested not to be asked about the incident. His father, Nelson, confirmed to the Pioneer Press that the victim was his grandson.
"I want to start off by saying I really appreciate all the support that I’ve been receiving from fans, the Vikings organization," Peterson said. "This is a private matter and I would ask y’all to please just respect my privacy and not ask at all about the situation at hand."
Despite the tragic news, Peterson said he was determined to play Sunday when the Vikings host the Carolina Panthers.
"I plan on playing Sunday. I will be playing Sunday, let me correct that. Be ready to roll, focused and ready to get a 'W' on Sunday, being 1-0."
Condolences to Peterson family.