Richard McCarthy says his 4-year-old son often received oral sex at school from a 5-year-old girl.
"He told me about all the bad things that girl had been doing to him," McCarthy said. "It went down in the classroom, it went down in the bathroom and it went down out on the playground."
At least one other boy at the First Lutheran Church of Carson School says he also received oral sex from the same girl.
"The two boys that have been introduced to this feeling that they don't know how to process are still looking for it, and trying to make it happen," McCarthy said.
The California Department of Social Services cited the school for at least one sexual incident between the kids, overall lack of supervision and an improper teacher-child ratio.
McCarthy and other parents are now joining attorney Greg Owen's lawsuit against the school and the church.
"To boil it all down, it comes to supervision," Owens said.
Parents are angry they were only given two weeks' notice that the school is shutting down for now. Church leaders wouldn't go on camera, but told Eyewitness News off-camera that there were only two incidents involving inappropriate touching among the kids, and those cases are closed.
They also said the school is closing because the director is leaving for personal reasons, and no teacher wants the job. They insisted student sex has nothing to do with the closure, something McCarthy said is a lie.
McCarthy says after the school told him his son was acting up again, he rushed to campus.
"I just had to keep yelling in his ear, 'You're not in trouble, you're not in trouble!' And I just told him, 'You're never coming back here again for these people to do this to you,'" McCarthy said, fighting back tears.
But now, he doesn't know where to send his son.
"There's no way I can just take him to another school and be that parent that just lets a predator loose," McCarthy said. "How else do you explain it?"
The school is set to close next Friday. Parents say the girl accused of the oral sex is no longer at the school.
Eyewitness News contacted the Department of Child Protective Services, but they said they legally could not comment on the investigation or on the welfare of the girl.
Owens plans to file the lawsuit on Monday.