CHIBA (Kyodo) -- Two men were injured Saturday in an explosion at an apartment building in Chiba Prefecture, east of Tokyo, with one suffering burns over his entire body, according to the local fire department.

The blast, which occurred around 6:35 a.m. in Ichikawa, damaged the three-story building's windows and walls. The fire department said the other man sustained minor injuries from broken glass.

The police and fire department are investigating the cause of the explosion, which appears to have originated on the first floor of the apartment building and damaged cars in its parking lot, as well as nearby houses and a school building.

The apartment building is in a residential area near Minami-Gyotoku Station of Tokyo Metro's Tozai Line.