OTSU, Shiga Pref. (Kyodo) An explosion at Kyocera Corp.'s solar-battery plant in Yasu, Shiga Prefecture, filled the building with smoke but caused no injuries, police said.

The blast, which occurred in the early hours of Monday at one of the plant's 12 operating furnaces, blew a hole in a ceiling. There were about 20 workers at the plant at the time and all escaped unharmed, according to the police and the major ceramics manufacturer.

They said the cause of the explosion wasn't immediately clear and were opening an investigation.