She also said she was glad her son is now "in a place where he can no longer do harm to anyone."
"To the families of the victims, I am so, so very sorry that this has happened.
"My heart is broken."
She took no questions after the statement, which she gave to a reporter in New York.
“His actions have had a profound and everlasting effect on the families of the victims,” she said. “I don’t know why he did what he did, and I’ll never be able to ask him why."
Celebrity Breakups and divorces of 2014 [PHOTOS]