Sarah Wu only learned a second grader had brought a knife to her son’s school earlier this month from another mom, who asked for her phone number after dismissal.

“The third message she texts me was, did you know that your child was the intended target? I was, I was devastated when I heard that, because I wasn't notified by school,” Wu told NY1.

It’s the latest in a string of incidents at P.S. 398 in Queens — including an exodus of staff documented earlier this year by the news outlet The City — that have left many parents demanding the removal of the school’s founding principal, Erica Urena-Thus.

The knife was confiscated Wednesday, Nov. 1. Urena-Thus only told parents about it three days later, in a message on Saturday saying “a sharp kitchen object” had been found in the school, but that “nothing untoward was found.” Parents were told the knife was meant to cut food.

But that contradicts what other students say happened. Maribel's daughter is in the same class as the boy who allegedly brought the knife. NY1 only uses her first name because of her concern for her child.

Speaking in Spanish, she told NY1 what her daughter told her: The boy showed her the knife, and told her he was going to use it to hurt Wu’s son in the bathroom during lunch.

"She can’t sleep, she is scared and in panic, and I am really concerned because the school doesn't give us any answers,” Maribel said. “I have been having to look for answers outside and in therapy.”

And now, after her daughter spoke up about what she saw, Maribel says her daughter has also been threatened.

"He told her he was going to kill her, but didn't know when and where,” she said, through tears.

The Monday after the knife incident, Urena-Thus, the principal, held a security meeting with parents, only to call police and issue a shelter-in-place order when they arrived.

A week later, parents showed up in force again — this time to ask for her removal at a meeting of the local Community Education Council.

Superintendent Lisa Hidalgo, who just took on the job this fall, was there listening. She said it was all being documented.

“As I've mentioned before, this is a process. And the process — unfortunately sometimes it's not as fast,” Hidalgo said. “However, I want you to know that we are leaning in. We are hearing you.”

Urena-Thus did not respond to a request for comment, nor did her union.

A Department of Education spokeswoman told NY1 every student deserves a safe and supportive learning environment.

“Our district superintendent assigned staff to support onsite at the school daily, reviewing protocols, and looks forward to next step interventions that best serve everyone,” the spokeswoman, Chyann Tull, said. “The borough safety director is also onsite reviewing safety systems and structures, performing an analysis of the school’s safety plan. High-quality care and education for our students is at the center of our efforts, and we will continue to support collaboration between schools and families as we forge a path forward.”

Parents like Wu say something needs to change, and fast.

“I think that because these kids are so young, we need someone that we could trust,” Wu said. “Because there’s no full transparency, no clear communication, nothing from this principal, this whole community of parents are very scared and worried. And we want someone to really thoroughly investigate this and look into this. And I don’t know if I could trust someone like her again.”