Eleven suspects were arrested after a month-long child sex crime sting in Pawnee County, Oklahoma, recently.

The Pawnee County Sheriff’s Office began its investigation when a middle school student turned in an older classmate for making a lewd proposal, according to News 9.

“That case led investigators to a social media app and to 11 men, who the sheriff says were targeting underage boys for sex,” the report noted.

The app, called Grindr, is “The world’s largest social networking app for gay, bi, trans, and queer people,” according to its website.

Sheriff Mike Waters said all of the men arrested knew or thought they were talking to underage boys on the app. However, some of them were actually messaging with an undercover deputy.

“It’s jaw dropping, it’s unbelievable,” Waters commented, adding, “The public needs to know; the parents need to know how dangerous this is.”

Two of the suspects, Thomas Muench, 25, and Quinton Griesel, 25, were charged with rape.

Griesel reportedly had sex with a 16-year-old boy in a bathroom stall at Pawnee High School when he worked for a food service vendor and served lunch in the school’s cafeteria.

Muench was accused of having sex with a 15-year-old boy, but not while they were on any school property.

Court records stated that the two suspects met the teenage victims on the Grindr app.

Pawnee and Osage County District Attorney Mike Fisher said law enforcement officers and schools can only do so much to prevent this kind of thing from happening to kids. He then urged parents to block apps on their children’s phones and know who they are talking to.

“Old-fashioned parenting is the best way to do it and that’s to stay in communication with your child, look at their phone. Don’t be afraid to do that,” he stated.

In September, Breitbart News published a list of the top 15 potentially dangerous apps parents should look for on their kid’s smartphones, which included Grindr.

“Many of the apps used are advertised for adults but can be easily accessed by children leaving them vulnerable to everything from unwanted sexual messages to online bullying,” the report concluded.

Tuesday, the charges against 29-year-old Keith Ray were dropped, according to an update by News 9.