Police in New York City have opened an investigation after human remains were unearthed at a construction site near a psychiatric hospital.

Police say workers were doing sewer repair work at the Brooklyn construction site when they found remains 13 feet (4 meters) below the surface Monday afternoon. Investigators say workers found a skull, arm and leg bones.

The city medical examiner later confirmed the remains found at the East Flatbush site belonged to a human. Authorities do not know how long the bones had been there. The construction site is near the Kingsboro Psychiatric Center.

Police continue to investigate.

(AP)