A man armed with a knife killed his mother and sister and seriously injured another person in a town near Paris on Thursday, officials said.
The man, who police said had been on a terror watch list since 2016, was later shot and killed after confronting police in Trappes.
The motive for the violence remains unclear, but the Islamic State group claimed the attack via its propaganda channel.
Experts urge caution about the group’s announcements, however, because it has lost credibility after recently claiming seemingly unrelated violence as it faces defeat on the battlefield in the Middle East.
“My first thoughts go to the victims and their loved ones,” Interior Minister Gerard Collomb wrote on Twitter. “I want to commend the security forces for their exemplary reaction and mobilisation.”
The man had been on the terror watch list after expressing extremist views, a police source said.
Trappes has a population of around 30,000 and is part of the far suburbs of the greater Paris area, lying about 30 kilometres southwest of the capital.