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NEW: "I wish I had known then what I know now," mother says

Dylan Klebold and Eric Harris killed 13 people and injured 24 in the attack on Columbine High School

This is her first television interview since the tragedy nearly 17 years ago

CNN —  

Her son and his friend killed 13 people at Columbine High School almost 17 years ago. Sue Klebold has lived with guilt since – guilt for what her son did and how she, a loving mother, raised a boy who became a mass murderer.

She has spoken only a few times to the media in the past, but has never appeared on television. Her first TV interview, given to ABC’s Diane Sawyer, aired Friday night.

In it she talks about what life has been like after April 20, 1999, when her son, Dylan Klebold, and schoolmate Eric Harris committed what is the deadliest high school shooting in U.S. history. Clad in black trenchcoats and wielding four guns, the pair worked their way through the Colorado school after their plan to blow up hundreds of classmates failed.