A human body has washed ashore on New York's tiny Plum Island, where a U.S. government lab studies dangerous animal diseases.

Police say a security guard discovered the clothed body Thursday afternoon on the island's southwest beach area where access is restricted.

Police on Long Island say an autopsy found no immediate cause of death but determined the partially decomposed body was that of a black male about 6 feet tall with a large build and very long fingers. They say there were no obvious signs of trauma.

Plum Island is about 100 miles northeast of New York City in the Long Island Sound. It has been called a potential target for terrorists because of its stock of vaccines and diseases, such as African swine fever.