ARVADA, Colo. (CBS4) – A 15-year-old student in Arvada is under investigation for cyber-bullying using Instagram.

Arvada police say the boy was charged with five counts of third-degree harassment. He is a student at Ralston Valley High. His name is not being released.

The charges stem from what’s called a burn book and it’s postings on Instagram under the user name “anonymous.”

“There was five student victims,” Jill McGranahan with Aravada police said.

The pictures of five Ralston Valley Students were likely taken from their Facebook page and uploaded to Instagram. Police say under each picture there was a caption with derogatory or sexual comments.

“We received a report of it almost immediately after it was created,” McGranahan said. “We were able to track the person who did that through their IP address.”

Police warn parents to talk to their children about using Instagram and tell them that even if they post something anonymously, it’s still possible to track down them down.