ELKHART COUNTY — It's something parents never think they'll have to deal with -- learning their child has been molested. But local police say they're investigating more cases involving kids who molest other kids.

One Elkhart mother said a 10-year-old boy had sex with her 4-year-old daughter. She said it happened when she left her daughter with a family friend in March.

"It's really hard ... knowing that happened to her."

The woman, whose identity is being withheld to protect her and her daughter, said the 4-year-old now says she feels dirty.

Madison Center Child Therapist Dennis Fehr said sexual abuse between kids happens more often than you might think.

"Kids will perpetrate on those they have access to," said Fehr. "It's usually people close at hand — it's siblings, it's cousins, it's friends, it's neighbors."

Detectives in Elkhart County are investigating three separate cases of molestation that allegedly happened this week.

According to police records: Monday an adolescent boy fondled an 8-year-old boy he didn't know in Concord Township; Wednesday a 4-year-old Goshen boy allegedly performed oral sex on an 11-year-old boy who asked him to do it; and Thursday an Elkhart mother caught her 9-year-old son in a sex act with another juvenile.

"You really don't want to believe that children can be perping on other children," said Tony Sommer, with the Department of Child Services.

The mom whose daughter was reportedly molested in March told WSBT she still can't believe it.

"I left her with somebody I trusted," she explained.

Even though her 4-year-old daughter is now in counseling, she still feels helpless.

"I can't begin to know how to talk to a 4-year-old about what happened because I don't know what to say or what to do to make things better," she said.

Police say that 10-year-old boy was arrested and taken to juvenile court. A prosecutor dismissed the case.

Failure to report a sex crime against a child is against the law.