Two people were killed and one seriously wounded in a knife attack in Trappes, a suburb west of Paris, French authorities said Thursday.
The assailant, armed with several knives, was shot dead by police.
"The police operation is over, the person was neutralized and is dead," the local prefecture said on Twitter.
The Islamic State group claimed responsibility for the attack, but two French officials, speaking on condition of anonymity, said that the two people killed in the attack were the attacker's mother and sister.
Police are investigating the possibility that the incident was a result of a family quarrel.
Local media reported that the attacker shouted "Allahu akbar" (Arabic for "God is great") before pouncing on his victims, but authorities could not immediately confirm the report.
"The reason behind the attack and his profile are not known yet and are being looked into," one official said.
Counterterrorism officials have yet to be asked to join the investigation, a judicial source said.
The assailant, believed to be a man in his 30s, barricaded himself in a building following the attack, only to emerge at around 10 a.m.
A security source said: "He disappeared into a house when police arrived at the scene and when he came out, he was shot dead."
Once they had the situation under control, police officers tweeted: "Avoid the area and do not to disturb the work of the policemen."
