The U.S. Department of Education's Office of Civil Rights is investigating how the Natrona County School District handled an unspecified incident involving students in 2015, the district's attorney confirmed Friday.

This week, K2 Radio received a tip confirmed by a credible source about the investigation that it falls under Title IX of the Civil Rights Act, regarding sexual harassment, sexual violence and retaliation.

Title IX forbids discrimination based on sex in educational institutions that receive federal funding.

The initial information K2 News received alleged that the incident was a sexual assault that was not investigated by school officials.

Attorney Kathleen Dixon refused to elaborate on the nature of the incident under investigation.

"In this circumstance, the school district is cooperating fully as we always do with any type of inquiry from any agency,"  Dixon said.

The Denver regional office of the Department of Education's OCR isn't investigating the incident itself so much as it is investigating how the school district handled the alleged incident, Dixon said.

"The Natrona County School District has policies related to anti-discrimination, anti-harassment, anti-bullying and that we also have procedures for investigations and I can tell you that those procedures were followed in this case," she said. "The OCR's investigation is into whether or not there were adequate policies and whether or not those policies were followed with regard to the investigations."

Dixon could not reveal specific information about the case, but it involves a complaint brought by students. "There are no staff members involved in the alleged incident."

She declined to say when or where the incident occurred, what the incident was about, and the number of alleged perpetrators and alleged victims.

The complaint was filed in July. Civil rights complaints take between four months and several years to resolve, Dixon said.

No local or state agencies investigated the alleged incident, she said. However, she declined to comment on whether the alleged incident was handled entirely within the district.

Dixon also declined to say whether the Office of Civil Rights has conducted other investigations of alleged incidents in the past five years.