MANILA, Philippines (AP) — A Philippine navy frigate has run aground on a shoal in the disputed South China Sea and efforts are underway to retrieve it and its crewmen, who were unhurt.

Military spokesman Col. Noel Detoyato says the BRP Gregorio del Pilar ran aground Wednesday night in the vicinity of the shoal, which the Philippines calls Hasa Hasa.

The barren shoal is known internationally as Half Moon Shoal and lies on the eastern edge of the hotly contested Spratly archipelago in the disputed sea.

Detoyato said late Thursday that Philippine ships "have already been mobilized to conduct assessment, retrieve the aground vessel and return her to safe harbor and assist all personnel aboard BRP del Pilar."