Authorities say an autopsy has been ordered after human remains were found on federal property south of Port Isabel on Wednesday.

Cameron County Sheriff Eric Garza said a crew was replacing a billboard off of Highway 48 when they flagged down a state trooper.

The Texas Rangers then contacted the Cameron County Sheriff's Office, who determined the area where the remains were found was inside Port Isabel city limits on federal refuge property.

"All it was, was bones, so it looks like there's no identification," Precinct 1 Justice of the Peace Benito Ochoa said. "They were classified as a John Doe."

The U.S. National Wildlife Refuge System was spotted at the scene Wednesday afternoon.