(CNN) -- French police are looking for a man Friday after bodies thought to be those of his wife and four children were discovered under the terrace of their family home in western France.
The bodies were found Thursday in jute sacks with the chemical compound quicklime. The bodies of what are thought to be the family's two dogs were found buried with them at the home in Nantes.
The family's car, which had been missing since the beginning of April, was discovered by police Thursday night in the Var region in the south of France. The blue Citroen was found at the Formula 1 Hotel at Roquebrune-sur-Argens.
No member of the Dupont family has been seen since April 4, police say. They include Xavier Dupont, 50; Agnes Dupont, 49; their two adult sons, Arthur and Thomas; their 16-year-old daughter Anne; and a 13-year-old son, Benoit.
The Nantes district attorney, Xavier Ronsin, said the five people found buried are presumed to have died by firearm, but the exact cause of death will be determined in autopsies Friday. He confirmed no other bodies were found under the terrace.
The Dupont family had never spoken publicly about leaving, before they disappeared, but messages described by Ronsin as "strange and contradictory" had been left by the family. Some explained that the family was withdrawing the children from school, others indicated they had immigrated to Australia, Ronsin said. The father also wrote to some of his relatives, announcing that he was a secret agent on behalf of the United States and he had to go overseas for an important drug-related trial.
Ronsin said no trace of struggle or violence has been found in the home, but brownish stains had been found in the house. In addition, all the cupboards had been emptied and computer hard drives were missing.
Didier Groleau, diocesan director of a catholic school where the younger siblings attended said: "At the moment people are extremely shocked by the events, they are in pain. We have put in place a psychological unit close to the school, in order to be able to treat the problems of young people who will have been shocked by the announcement."
Pupils have been laying down flowers, notes and photographs outside the school in memory of their classmates.