Jacob Hall was hit in a femoral artery and a massive blood loss led to a major brain injury. He died Saturday, Renae Hall wrote on Facebook.
"You are dead to me by God you are my angel and now as I lay here and Watch the Life leave your body it reminds me of how honored I was to have you in my life," she wrote in her post.
A family statement added thanks to doctors and the community. It said Jacob was an example of "pure love."
"He showed us how to love, laugh and smile even on days we did not want to," Renae and Rodger Hall said. "God gave him to us and he was taken away from us by a senseless act. We know that Jacob has already forgiven this child for what he did to him and his family because that's the kind of child he was."
The 14-year-old boy suspected of the shooting at Townville Elementary School was charged Friday with three counts of attempted murder. He was also charged with murder in connection with the killing of his father at the family home.
CNN is not naming the accused shooter because he is a minor. His case is being heard in family court, and it is not yet clear whether he will be tried as an adult.
Jacob was one of three people shot when the teen opened fire on the school playground Wednesday. Another student and a teacher were treated and released on the day of the shooting.
Authorities said they believe the teen shot his father, then took a pickup to the school in the small community of Townville, where he began firing as he got out of the vehicle.
The wounded teacher -- who was shot while trying to protect Jacob and other children -- was identified as Meghan Hollingsworth, who teaches first grade and has been at Townville Elementary for nine years.
Townville is in Anderson County, not far from Greenville and close to the border with Georgia.