TOKYO (AP) _ A World War II artillery shell that a boy had kept in his toy box for six months exploded when he took it out to play, and police said the blast killed him, injured his father and destroyed their home.

The Japanese Imperial Army shell exploded on Sunday, blowing out the walls and windows of the boy's home in Obihiro in northern Japan.

The boy - 9-year-old Takahiro Shibuya - died from head injuries, and his father, Satomi, 38, was injured in the stomach and one hand when fragments of the shell hit him as he was walking outside the home.

Policeman Shinobu Kusakabe said the boy had kept the rusty 5-by-2 inch shell in his toy box since October. It not known where the boy found the shell.