Shortly after a writer from “One Tree Hill” came forward with allegations of sexual harassment against show creator Mark Schwahn, 18 women from the cast and crew have joined her in speaking out.

Audrey Wauchope, who was one of the writers for the hit drama series, came forward with her allegations on Twitter over the weekend, but never mentioned Schwahn’s name. On Monday, the show’s stars Sophia Bush, Hilarie Burton and Bethany Joy Lenz and more than a dozen others all backed Wauchope’s claims, revealing it was Schwahn in a letter sent to Variety.

“Many of us were, to varying degrees, manipulated psychologically and emotionally,” the letter said. “More than one of us is still in treatment for post-traumatic stress. Many of us were put in uncomfortable positions and had to swiftly learn to fight back, sometimes physically, because it was made clear to us that the supervisors in the room were not the protectors they were supposed to be. Many of us were spoken to in ways that ran the spectrum from deeply upsetting, to traumatizing, to downright illegal. And a few of us were put in positions where we felt physically unsafe. More than one woman on our show had her career trajectory threatened.”

It’s time, sisters. I am so proud to call these women my family. You cannot imagine. #linkinbio https://t.co/OvWGsCyuXb

— Sophia Bush (@SophiaBush) November 14, 2017

I have been angry for a decade. Today, my sisters take back what was rightfully ours. #burnitdownsis #fuckyoursorry https://t.co/QMZBzwqm7g

— Hilarie Burton (@HilarieBurton) November 14, 2017

What a long time coming. Your deeds will truly find you out in the end. I’m grateful for the opportunity to speak up in a time when change is possible. There is still more to say but for this moment, we thank you for your support

— Bethany Joy Lenz (@BethanyJoyLenz) November 14, 2017

In her series of tweets, Wauchope said she was told that Schwahn brought her and another female writer on the show because of their looks and were told Schwahn “wants to f**k you.” The writer, who now works on “Crazy Ex-Girlfriend,” also claimed that he often groped the women of the cast and crew and frequently showed the men on the show nude photos of the women he was sleeping with.

“All of the female cast members of ‘One Tree Hill’ have chosen this forum to stand together in support of Audrey Wauchope and one another,” the letter from Wauchope’s “One Tree Hill” colleagues said. “To use terminology that has become familiar as the systemic reality of sexual harassment and assault has come more and more to light, Mark Schwahn’s behavior over the duration of the filming of One Tree Hill was something of an ‘open secret.'”

“Many of us since have stayed silent publicly but had very open channels of communication in our friend group and in our industry, because we want Tree Hill to remain the place ‘where everything’s better and everything’s safe’ for our fans; some of whom have said that the show quite literally saved their lives,” the letter continues. “But the reality is, no space is safe when it has an underlying and infectious cancer. We have worked at taking our power back, making the conventions our own, and relishing in the good memories. But there is more work to be done. We are all deeply grateful for Audrey’s courage. For one another. And for every male cast mate and crew member who has reached out to our group of women to offer their support these last few days. They echo the greater rallying cry that must lead us to change: Believe Women. We are all in this together.”

According to Wauchope, the show held mandatory sexual harassment training, which the cast and crew hoped would solve their problems, but Schwahn didn’t attend. The “One Tree Hill” creator now works on “The Royals” on E!.

“We are monitoring the information carefully,” the network said in a statement regarding the allegations against Schwahn. “E!, Universal Cable Productions and Lionsgate Television are committed to providing a safe working environment in which everyone is treated respectfully and professionally.”