A policeman and his wife were killed in a frenzied knife attack at their home in a Paris suburb on Monday night by a man who reportedly shouted "Allahu Akhbar".
The couple's three-year-old son was rescued after police stormed the home in the north-western Paris suburb of Magnanville and shot dead the attacker.
He stabbed the 42-year-old officer, who held the rank of "commandant" (commander), nine times in the stomach at his front door. After stabbing the policeman, the attacker forced his way into the home.
It was unclear how the policeman's wife was killed. She worked as a secretary at a local police station.
The child was rescued and was "shocked but unharmed", the interior ministry spokesman, Pierre-Henry Brandet, said.
Five detonations or shots were heard by millions on live television while Mr Brandet spoke to reporters as police stormed the home.
"Negotiations were opened but it became clear that they would not succeed and police then entered the home, where they found the body of a woman," Mr Brandet said.
Police sources said the attacker, who has not been named, was a former soldier and a neighbour of the couple.
Some sources described the attacker as a neighbour of the policeman, who was in plain clothes when he was killed. Witnesses heard the assailant, described as a teenager or in his early 20s, shout "Allahu Akhbar", Arabic for God is great.
However, the local prosecutor, Vincent Lesclous, said the killing was being treated as a criminal case rather than terrorism.