An Emmaus High School sexting scandal started with boys sharing photos of ex-girlfriends, multiple sources have told Patch.

Some of the students involved did not show up for school on Monday, sources also said.

Police are investigating how nude photos of students wound up on an international porn Web site.

Students say they've known about the Web site for weeks and that the site is still active.

One student tweeted about how uncomfortable it is to walk around school knowing classmates have seen her naked. WFMZ reports that some students are bragging about being on the site while others are distraught.

That's why East Penn School District Superintendent Thomas L. Seidenberger wants parents and students to know that cyberspace is a dangerous and unforgiving place.

"If a young person makes a mistake, it is out there for all the world to know," he said. "It’s sad. And it’s sad that these kids are going to have to face the consequences. But maybe some other young people can learn from their mistakes. Maybe some parents can use it as a teachable moment and have a conversation with their kids.”

Seidenberger said the investigation is "really a police matter” and that he’ll “take his lead from the police department."

“If it happened on school district time, then we’ll deal with it,” he said.

Seidenberger told WFMZ that other school districts are involved in the investigation.

Sgt. Karl Geschwindt of the Emmaus Police Department said the investigation is ongoing. He would not comment further.

A 15-year-old Emmaus High School student took hundreds of photos and videos up girls’ and teachers’ skirts and posted them on the Internet in 2009.

Parkland High School was the scene of a 2008 police probe after sexual images were sent out to more than 40 students through cell phones.