According to details released by France's Interior Ministry the killing of the French policeman occurred at around 8.30pm on Monday in the small town of Magnanville, to the west of Paris (see map below).
According to reports the attacker lay in wait for the officer, named Jean-Batiste Salvaing, by hiding behind the gate to his house.
As he was returned home, the suspect brutally attacked him, stabbing him repeatedly in the abdomen. The policeman, who was dressed in civilian clothing, apparently put up a struggle and managed to escape the clutches of his attacker and tell neighbours to call the police. But he was then caught again and killed on the pavement outside his home on allée des Perdrix.
“The murder happened just outside his house. The suspect then holed up inside the house with two people, the policeman's partner and their three-year-old son,” a police source told L'Express magazine.
An elite police SWAT team was then dispatched to the scene and a security perimeter was set up around the house. Electricity and gas were cut off and nearby residential homes were evacuated. All roads were blocked off.
Police officers tried to negotiate with the suspect but in vain. At around midnight the police commando unit stormed the house of the building hoping to free the wife and son. Witnesses reported hearing loud explosions and the attacker was killed in the raid.
Inside the house police discovered the body of the policeman's wife. It is believed she had had her throat cut. The three-year-old son was found unharmed but in shock.
Why is this being considered a possible jihadist killing?
Speaking on Tuesday morning France's interior minister Bernard Cazeneuve described the brutal murders as "an appalling terrorist act".
French police first realized that they may not be dealing with an ordinary crime of murder when witnesses to the stabbing said the suspect shouted “Allahu Akbar” (God is greatest) as he launched his terrifying attack.
Later it then emerged that the attacker had claimed allegiance to the Islamic State group in negotiations with police officers.
"The anti-terror department of the Paris prosecution service is taking into account at this stage the mode of operation, the target and the comments made during negotiations with the RAID," one source said.
A short while later it appeared that Isis itself had claimed the attack.
The SITE Intelligence Group, a US-based monitor, cited the Isis-linked Amaq News Agency as saying on its Telegram channels: "Islamic State fighter kills deputy chief of the police station in the city of Les Mureaux and his wife with blade weapons near #Paris."
L'Etat islamique revendique l'attentat de Magnanville en France (Amaq) pic.twitter.com/uRq4MtAEKt— David Thomson (@_DavidThomson) June 14, 2016
Police sources have since told French media that the attacker had already served prison time for his links to jihadist groups.
He had been sentenced in 2013 for taking part in a jihadist organisation with links to Pakistan.
According to David Thomson, a specialist in jihadism, the attacker posted images of his victims on Facebook, along with a 15-minute video in which he claimed responsibility for the attack and urged other followers of Isis to follow his lead.
What do we know about the attacker?
The man had been sentenced in 2013 for taking part in a jihadist organisation with links to Pakistan, sources said on Tuesday.
They identified him as Frenchman, Larossi Abballa, 25, adding that he had been sentenced to a three-year term -- six months of which were suspended – for "criminal association with the aim of preparing terrorist acts," in a trial with seven other defendants.
AFP were also reporting that Abballa was part of a probe into a network sending jihadists to Syria.
What do we know about the victims?
The policeman who was killed was the deputy head of the police at Les Mureaux, a town not far from Magnanville where he lived.
He was named in the French press only as Jean-Batiste Salvaing, aged 42 years old and described as “very friendly with a good reputation” by colleagues.
His partner, named as Jessica, aged 36, also worked with the police service as an administrator at nearby Mantes-la-Jolie police station, where her husband had previously worked.
Their three-year-old son Mathieu was found unharmed, but in shock and was transported to hospital in Paris to receive treatment.
What we don't know
As always in the early stages of the investigation there appears to be more that authorities don't know or perhaps have not revealed, than what we do know.
Was there a reason the attacker chose his victim? Were they known to each other? A police spokesman said on Tuesday that he believed the attacker had no previous connection to his victims.
Reports on Tuesday morning claimed the couple had reported a break-in at their home before the attack, although it is not known when.
One important question, given the suspect's apparent past, is whether he was being closely monitored before the attack. Did he give any signs he was about to act?
And French counter-terror police will also want to know whether he was in contact with anyone in Isis in the Middle East. Was the attack ordered? Did he have a contact who guided him?
Isis has previously appealed for followers to launch any kind of attack in France, with any kind of weapon, in particular against figures of authority like police officers.
Importantly investigators will need to quickly ascertain if he was acting alone and not part of a network that may be preparing similar attacks.
A French politician, Bruno Retailleau from Les Republicains party, has already said the attacker was "a lone wolf" and had no network, unlike those who carried out the Paris and Brussels attacks.
Interior Minister Cazeneuve suggested more arrests would surely follow in the hunt for any accomplices.
President Francois Hollande said in a statement that "all light will be shed on the circumstances of this terrible tragedy," he added, announcing a meeting of top officials at the presidential palace early Tuesday.
A spokesperson from the Magnanville Town Hall told The Local that a press conference was scheduled for Tuesday afternoon, and had no further comments.