A relative of the family discovered the father in the garage where he had hanged himself. His wife, her mother and two children aged 7 and 10 years old were found dead in different rooms of the house.
According to a police source quoted by Le Parisien, the other family members were stabbed to death and were found on Tuesday evening.
The father, a computer scientist, had set up a device to hang himself and had even tied his hands in front of himself to make sure his suicide attempt was successful. This detail led the police investigators to suspect he had carefully planned the deaths.
The father was struggling at work, said a source quoted by Le Parisien, but the investigation into the deaths is still ongoing.
In the Piedalloues district, where the family lived, the neighbours were shocked on Wednesday morning. They say the family was discreet and seemed very united.