Ferguson also specified that her 16-year-old son was shot in the head.
She told ABC News on Wednesday that she had forgiven suspected shooter T.J. Lane.
"I would tell him I forgive him because, a lot of times, they don't know what they're doing. That's all I'd say," Ferguson said.
"I taught Demetrius not to live in the past, to live in today and forgiveness is divine. You have to forgive everything. God's grace is new each and every day," she said. "Until you've walked in another person's shoes, you don't know what made him come to this point."
Lane was officially charged today with three counts of aggravted murder, two counts of attempted aggravated murder and one count of felonious assault.
Students and parents gathered in the center of Chardon today to march back to the school together. The school was open today a walk through and parents and students were encouraged to come together. On Friday, school will be back in session.