A police officer and three others believed to be firefighters were found dead after fire ripped through a warehouse early Sunday in Shizuoka Prefecture, local police said.
The officer and the firefighters entered the warehouse at a factory operated by household product maker Lec Inc. in the town of Yoshida before flames engulfed the building.
Local authorities said they are trying to identify the three bodies as they believe they could be the three firefighters who have been missing since the fire broke out.
Three other firefighters sustained minor injuries due to the fire that was brought under control 16 hours after it broke out.
The fire department received an emergency call reporting the fire around 1:35 a.m. The warehouse, where sponges and sodium bicarbonate for household use were stored, was empty at the time, according to local police and Lec.