Denver Public Schools called the decision to investigate the conversion of a women’s restroom into an all-gender facility as potential discrimination “unprecedented.”

OCR initiated the probe after a Denver local news report about the creation of the restroom that included a complaint from a parent.

The U.S. Education Department said it is investigating Denver Public Schools for alleged discrimination after the district converted a girl’s restroom on the second floor of East High School into an all-gender restroom while leaving the other bathroom exclusively for male students.