Three people, all from the same family, were found dead on Thursday in a suspected murder-suicide in their house in the city of Hirakata, Osaka Prefecture, police said.
Firefighters, who received an emergency call at around 2:40 a.m., found them in the two-story residence showing no signs of life. A 48-year-old man, his wife and their daughter were later confirmed dead at a nearby hospital.
According to the local police, the couple's 16-year-old son, who lives at the house, made the emergency call, saying that his sister was screaming.
All four were living together at the house and there were no signs that someone had entered the house from the outside, the police said.
The man and his 20-year-old daughter were found on the second floor, while his 49-year-old wife was discovered on the first floor.
The knife apparently used in the stabbing was found near the man's body inside the residence, the police said.
Kyodo News decided to withhold his name after taking into consideration the nature of the case and its ramifications on his surviving underage son.