Attorney Greg Owen said families for four girls and two boys have joined his lawsuit against the school, which is set to be filed Tuesday morning.
"Each and every child who has talked to their parent has the exact same story," Owen said.
After seeing the story first reported by Eyewitness News on Friday, the Los Angeles County Sheriff's Department launched an investigation into allegations of sexual activity among children at the school.
Parent Richard McCarthy said his 4-year-old son often received oral sex at school from a 5-year-old girl. Owen said there were multiple girls involved in the oral sex acts on multiple occasions.
Sheriff's department Sgt. Dan Scott said the investigation would include interviewing the children, their parents and staff members who may have information on the incidents.
"I never expected to have this talk with her at 5," said the mother of the girl, who was caught by a teacher performing oral sex on the boy inside a bathroom.
The mother, who spoke exclusively with Eyewitness News but did not want to be identified, said her daughter told her she saw another girl at school do it.
The mother said investigators found no evidence of child abuse at her home. She provided Eyewitness News documents from the County of Los Angeles Department of Children and Family Services showing the case was closed as inconclusive.
The First Lutheran Church of Carson School was cited by the California Department of Social Services for a sexual incident between kids. However, the girl said she didn't think it wasn't an isolated incident.
"The way that she explained it, it was kind of like it was an everyday thing," the mother said. "Not oral sex, but from pulling the pants down to exposing themselves to, you know, trying to get somebody to put their mouth on the privates."
Eyewitness News first broke this story on Friday when Richard McCarthy said his son received oral sex at the school multiple times.
"It went down in the classroom, it went down in the bathroom, and it went down out on the playground," said McCarthy.
School officials said they were aware of only two incidents.
The school itself is set to close on Friday because the director is leaving for personal reasons and no teacher wants the job. They insist student sex has nothing to do with the closure.
A spokesman for the state regulating agency that cited the school said the school itself asked to be put on inactive status on Feb. 1 during a non-compliance conference that had been set up by the agency. The spokesman said that even though the school is closing for now, their investigation is not and more citations could soon be on the way.
Child psychologist Dr. Sheyda Melkonian said this case should remind all parents to talk to their children about good touching and bad touching.
"Let them know that I'm not going to get mad at you, I'm not going to penalize you for telling me this. But if you tell me and we talk about it, then I can help you see if this is something appropriate or if this is something inappropriate," she said.