DENVER — The mother of Columbine High School shooter Dylan Klebold says she didn’t know anything was wrong with her son before the 1999 attack.

In an interview that aired on “20/20” late Friday, Sue Klebold told ABC News’ Diane Sawyer that before the attack she considered herself a parent who would have known something was wrong.

“I think we like to believe that our love and our understanding is protective, and that ‘If anything were wrong with my kids, I would know.’ But I didn’t know, and it’s very hard to live with that,” she said.

“I felt that I was a good mom ... That he would, he could talk to me about anything,” she continued. “Part of the shock of this was that learning that what I believed and how I lived and how I parented was an invention in my own mind. That it, it was a completely different world that he was living in.”

Dylan Klebold and Eric Harris opened fire at the suburban Denver school on April 20, 1999, killing 12 students and a teacher before killing themselves. Another 24 people were injured in the attack.

Sue Klebold said that when she heard that her son was hurting others and that the attack might still be under way, she prayed that he would die so the violence would stop.

“There is never a day that goes by where I don’t think of the people that Dylan harmed,” she said, adding that, “It is very hard to live with the fact that someone you loved and raised has brutally killed people in such a horrific way.”