April 15, 2003 -- Nearly 10 years to the day that the Branch Davidian compound near Waco, Texas, went up in flames — killing 75 people, including 25 children — ABCNEWS' Charles Gibson interviews seven children who escaped the horror in an hourlong report on this week's Primetime Thursday, airing at 10 p.m. ET on ABC.

Brought together for the first time, they share stories of the bizarre world created by cult leader David Koresh and discuss living with the realization that their parents were willing to abandon them to follow Koresh to their graves. In addition, these survivors confront the former FBI agent who was in charge of the failed negotiations with Koresh — the first time someone involved in the siege has agreed to meet with them face to face.

Primetime will also air never-before-seen footage of the children's disturbing therapy sessions from 1993, which demonstrate the eerie effectiveness of Koresh's brainwashing techniques.

The seven survivors tell Gibson life in the compound was horrific. Physical abuse was a common occurrence, and there was no running water or indoor plumbing, they say. No attempt was made to provide the children with an education.

"When I left at age 18, I probably had an eighth-grade education," says Brad Borst.

In fact, Koresh made sure they were completely isolated from the outside world. Koresh brainwashed the children into thinking everyone outside of the cult was evil, and he prepared them for what he described as a final battle that would end the world and bring them eternal glory. Koresh threatened to kill the children after his resurrection if they helped the "bad guys."

Kiri Jewell, now 22, says she was sexually abused by Koresh when she was 10 years old and groomed to be his youngest wife — with her mother's consent.

The memories of life with Koresh are still vivid in her mind. "He never was very specific, but at some point we were gonna have to die for him," Jewell, now a student at Michigan State University, tells Gibson. "I didn't expect to live past 12."

Gibson also talks with 14-year-old Sky Okimoto, Koresh's own son, who was revered as a son of God inside the compound.

Borst describes how he left the compound. "I got on the bus in Waco and I never looked back," he says. "I knew that when I got on that bus that I was probably saving my life." His mother Jean stayed behind and perished in the fire.

Some of the survivors still feel anger toward the government. "I watched my mother die on television," says Borst. "I can still see that image today. And I will remember it the rest of my life."

Byron Sage, the former FBI negotiator who communicated with Koresh, regrets the tragic end of the standoff, but tells the survivors that law enforcement is ultimately not to blame.

"It's tragic that anybody had to die at Waco," he says. "It was just plain unnecessary and I regret it deeply."

But, Sage adds, "We did nothing that was malicious, we did nothing to try to intentionally harm, let alone kill, anybody. Our job was to resolve this thing peacefully."

Looking back, Sage says the biggest mistake he and his colleagues made was underestimating Koresh.

"I think that he was a con man," Sage tells the survivors. "The tragedy is that your loved ones did believe his message and they were willing to die for it."