PITTSBURGH — Three transgender seniors at Pine-Richland High School have sued the district for changing its rules about which restrooms they must use.

The Pine-Richland School District isn’t commenting on the federal lawsuit filed Thursday. It grew out of a school board resolution passed last month that makes students use restrooms that “correspond to their biological sex or unisex facilities.”

Previously, the district had allowed transgender students to use the restroom corresponding to their “gender identity.”

Two 18-year-old plaintiffs were born biologically male but identify as female, and one 17-year-old was born biologically female and identifies as male.

The lawsuit contends they were “designated” male or female based on their physical appearance alone at birth and are being discriminated against and marginalized by the new policy, which their federal lawsuit seeks to reverse.