Police in College Place, Washington, believe they've stopped what could have been another school massacre. A 17-year-old boy is under arrest after being turned in by his mother. Tonight she is speaking out.

"I know a lot of people that go to College Place High School. Their lives would have been forever changed," Nicole said. Nicole only wanted us to use her first name. "It's devastating. I know I did all I can do and that I made the right choice," she added.

That choice was calling the police after finding and reading her son's journal. He wrote about attacking his school on a specific date: April 20, 2020 — the anniversary of Columbine.

The journal went into chilling detail. He would detonate pipe bombs, and use multiple firearms to "blast anyone in sight" and "execute survivors."

When asked how it feels as a mother to turn her son in, Nicole responded, "Like I've done something wrong."

Police believe she did everything right.

"She's very courageous," said Troy Tomaras, College Place Police Chief. "It's clearly very emotional for her. She loves her son."

Nicole said she wrestled with making the phone call to police. She said her son told her it was only a creative writing exercise and that it was all "just a story."

"Well, he's plotting to attack and kill people. That's beyond creative writing. That's beyond normal," said Tomaras.

The 17-year-old's mother claimed he'd been battling depression.

"I'm worried about his mental health and he needs help," Nicole said, admitting that he's safer right now in jail than at school. "Truth hurts sometimes."

"It takes a lot to do what I did," she said, adding that she still loves her son. "It wasn't easy."

Tomaras said Nicole's actions saved people's lives.

"Absolutely, very courageous, very grateful," he said.

So are all of the students, teachers and staff. They have been saved by possibly the toughest choice a mother can make.