A 2-year-old boy died Dec. 9 in an apparent accidental shooting involving a rifle at his home in Meguro Ward, Tokyo, police said.

Naoki Tatematsu was hit in the right side of his chest in the living room where his father, Hideki, a 39-year-old doctor, had been cleaning four guns that he left on a table before briefly leaving the room, according to police.

The victim and his 5-year-old brother entered the room and the rifle was fired just as the father returned, police said. Investigators are looking into the possibility that the brother may have mistakenly pulled the trigger when he touched the rifle, they said.