Clouds of black smoke billow from Shoko Maru, a 998-ton Japanese oil tanker, after it exploded off the southwest coast near Himeji port, western Japan, Thursday. Pic: AP.

TOKYO (AP) — The coast guard says a Japanese oil tanker has exploded off the country’s southwest coast near Himeji port, leaving one of the eight people aboard missing and the other seven injured.

Public broadcaster NHK says four of the injured people were severely burned.

Photos and video from the scene Thursday morning showed billowing clouds of black smoke as coast guard vessels sought to douse the fire, which gutted the middle of the Shoko Maru, a 998-ton tanker based in the western city of Hiroshima.

The coast guard said the cause of the explosion was not yet known. NHK said crew members were working on the deck of the tanker at the time of the blast.