OSAKA (Kyodo) -- A man died when a tugboat and a pleasure boat collided in the Seto Inland Sea in western Japan on Sunday morning, the coast guard said.

The captain of the tugboat made an emergency call around 5:45 a.m., the local fire department said, adding of the four people recovered from the pleasure boat, one person had died, two were unconscious and another had suffered minor injuries.

The pleasure boat sank after colliding with the 16-meter-long, 19-ton tugboat off Yamaguchi Prefecture. As the coast guard searched the area with patrol ships and helicopters, one of the unconscious individuals was found by a diver inside the pleasure boat.

A dense fog advisory was in effect for the prefecture on Sunday morning.