According to reports, a Japanese oil tanker exploded today off the country's southwest coast near Himeji port, leaving one of the eight people aboard missing, the coast guard said. Four others are reported to be  severely injured.

Photos and video from the scene 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.

Seven people were rescued, though four suffered severe burns, public broadcaster NHK reported. A search was underway for the missing man, the tanker's captain, it said.

According to coast guard spokesman Koji Takarada the cause of the explosion was unclear, local news agencies said crew members were working on the deck of the tanker at the time of the blast.