Susan Klebold, the mother of 1999 massacre shooter Dyland Klebold, broke her silence in an essay entitled I will Never Know Why and published in O, The Oprah Magazine.

Klebold's essay talks about the day of the tragedy, her son's suicide, depression and the way the incident has affected her life ever since.

She admits I'd had no inkling of the battle Dylan was waging in his mind.

For the rest of my life, I will be haunted by the horror and anguish Dylan caused. I cannot look at a child in a grocery store or on the street without thinking about how my son's schoolmates spent the last moments of their lives. Dylan changed everything I believed about myself, about God, about family, and about love, Klebold's writes in the essay.

Klebold's essay has sparked strong emotions for survivors and parents of teenagers injured in the killings. But overall, it has been appreciated by them, according to the Associated Press who quotes Connie Michalik, the mother of Richard Caslado who was partially paralyzed in the rampage.

The following are excerpts from the interview published Wednesday in O, The Oprah Magazine's website:

On the day of the tragedy:

Early on April 20, I was getting dressed for work when I heard Dylan bound down the stairs and open the front door. Wondering why he was in such a hurry when he could have slept another 20 minutes, I poked my head out of the bedroom. 'Dyl? ' All he said was 'Bye.' The front door slammed, and his car sped down the driveway. His voice had sounded sharp. I figured he was mad because he'd had to get up early to give someone a lift to class. I had no idea that I had just heard his voice for the last time.

On her son's depression:

From the writings Dylan left behind, criminal psychologists have concluded that he was depressed and suicidal. When I first saw copied pages of these writings, they broke my heart. I'd had no inkling of the battle Dylan was waging in his mind.

On her son's suicide:

Dylan's participation in the massacre was impossible for me to accept until I began to connect it to his own death. Once I saw his journals, it was clear to me that Dylan entered the school with the intention of dying there. And so in order to understand what he might have been thinking, I started to learn all I could about suicide.