A preschool is shutting down after allegations of sexual activity between students were reported.

Richard McCarthy says his 4-year-old son received oral sex from a 5-year-old girl several times as a student at First Lutheran Church of Carson School, according to ABC 7. At least one other boy at the school reported that the girl had done the same thing to him at the school in Carson, California.

McCarthy told ABC what his son told him: "It went down in the classroom, it went down in the bathroom and it went down out on the playground."

Now McCarthy and the parents of three other students are filing a lawsuit against the school and church, alleging that their students weren't being adequately monitored. The suit, which the attorney says will be filed tomorrow, claims that there were times when school aides were literally sleeping on the job.

"It all boils down to a lack of supervision," attorney Greg Owen told ABC News. "There were times when teachers would let aides in the room for hours at a time to watch the kids. During naptime, the aides would be sleeping and the children would have been molesting each other during this time."

The California Department of Social Services has cited the school in the past for a lack of supervision and an improper teacher-to-student ratio. It has also cited the school for at least one sexual incident between students.

The school announced that it is closing next Friday, and it gave parents two weeks' notice. School officials told ABC 7 that the closing had absolutely nothing to do with the allegations. The school says the director of the school resigned for personal reasons and could not find a teacher who would take over. Parents don't buy that explanation given the timing and are angered that they were given so little notice about the school closing mid-year.

McCarthy said he is worried about sending his son to another school, because he is worried that his son might try to molest other students at another school.

"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 told ABC 7. He added, "There's no way I can just take him to another school and be that parent that just lets a predator loose. How else do you explain it?"

The young girl accused of oral sex is no longer at the school. The Department of Child Protective Services cannot legally comment on the investigation or the girl's background.