The man who killed a French police couple at their home near Paris was responding to calls by so-called Islamic State (IS) “to kill infidels”, police say.
Larossi Abballa, who was killed in a shootout with police, was loyal to IS leader Abu Bakr al-Baghdadi, they said.
A police commander and his partner were stabbed to death at their home. Their three-year-old child survived.
The killings were “a terrorist act”, President Francois Hollande said.
France still faced “a significant threat”, he said.
The attacker was killed in an police assault on the house in Magnanville, about 55km (35 miles) north-west of the French capital.
He had spent time in jail over jihadist links and had a list of targets including public figures, police say.
He had also been under recent police surveillance, including a wiretap, media reports say, quoting police sources.
Paris Prosecutor Francois Molin said Abballa had pledged his loyalty to the IS leader during negotiations prior to the police assault on Monday.
Three people linked to the man have been arrested and placed in custody, police said.