Three French officials identified the two people killed in the attack in Trappes and the mother and sister of the attacker. The official spoke on condition of anonymity because he wasn't authorized to discuss such details publicly.
The Islamic State group claimed that "the person who carried out the attack in Trappes, southwest of Paris, was an Islamic State fighter". The tweet also said two of the attacker's victims were killed and another seriously injured.
PARIS -A man in the Paris suburb of Trappes used a knife to kill his mother and sister and he was killed by police.
Islamic State claimed responsibility for the attack, according to the SITE Intelligence Group, which monitors extremist media - though the terrorist group has often claimed responsibility for attacks despite having no clear link to the actual attacker.
"A man attacked passers-by in rue Camille Claudel in Trappes".
About 15 miles west of Paris, Trappes is on a government list of 30 crime-ridden districts across France that need more police presence.
The leader of the extremist group Abu Bakr al-Baghdadi had called on Muslims to wage "jihad" in a purported new audio recording released on Wednesday.
The Islamic State's claim Thursday was issued before authorities confirmed that the attacker's two victims were his relatives.
French Interior Minister Gerard Collomb tweeted that the attacker had been neutralized without saying if he was dead.
BFM TV said the attacker shouted "Allahu Akbar", but police could not confirm this, and they said investigators were looking into whether this was a family quarrel.
French police establish a security perimeter around a residential pavilion in France, Aug. 23, 2018.