"I was aware of what I was doing, but I could not stop myself. I was in a major rage and pissed off, pissed off at my whole life and everybody that's hurt me and blew up, and I hurt the wrong people," he said in the interview.
Gardner pleaded guilty earlier this month to the murders of 17-year-old Chelsea King and 14-year-old Amber Dubois. Chelsea disappeared on February 25 when she went for a jog. Her body was discovered five days later in a shallow grave - she had been strangled.
Three days after Gardner was arraigned on charges of killing Chelsea, he led police to Amber's skeletal remains because he said he felt bad. The Escondido High School student was abducted 13 months earlier walking to school.
During the interview, Gardner criticized school budget shortfalls as if it played a role in Amber's murder. He said had Amber taken the bus that day, she might still be alive.
"I hate myself. I really do. There is no taking back what I did. And if I could, yes I would, are you kidding me?" he said. "But I was out of control. If I was able to stop myself in the middle of it, I would have. And I could not. I was out of control."
Gardner claims authorities delayed telling his victims' families about his confession, prompting him to call the attorney general's office to complain. He only wants to discuss details of the killings with the families, if they ask.
When asked if there are any other victims, Gardner said, "Good try," and laughed.
Amber's mother said she has no plans to meet with Gardner, but said she does want answers.
Gardner will be sentenced on May 14 to life in prison without parole as part of the plea deal.