A 45-year-old man employed at police headquarters in central Paris fatally stabbed four officers today before being shot dead by police, officials have said.
The IT assistant killed three male officers and a female administrative worker in a building close to Notre-Dame Cathedral before he was killed.
Another person was wounded and has undergone surgery.
Officials said there are investigating if there is a terrorism link.
French broadcaster BFM TV said the attacker had converted to Islam 18 months ago.
Investigators suspect a workplace row sparked the deadliest attack on police in France in years.
Paris prosecutor Remy Heitz.said police were searching the attacker's home, and that anti-terrorist investigators were evaluating what had happened, for any terrorist links.
The attacker's wife had been brought into police custody but not charged, the prosecutor's office said.
French Interior Minister Christophe Castaner said the attacker was known to his colleagues and had worked for some time in the IT department.
Jean-Marc Bailleul, a police union leader, described the incident as criminal rather than an act of terrorism.
"It was a moment of madness," Mr Bailleul told BFM TV.
In the past four years, Paris has been rocked by violent attacks resulting in mass casualties.
Coordinated bombings and shootings by Islamist militants in November 2015, at the Bataclan theatre and other locations around Paris, killed 130 people in the deadliest attacks in France since World War Two.
Over a three-day period n January 2015, Islamist gunmen killed reporters and illustrators at satirical weekly newspaper Charlie Hebdo, police officers, and shoppers at a Jewish supermarket.
