Four officers including a woman were stabbed to death on Thursday at the police headquarters in Paris, above, by an administrative officer working in its IT department.
Another officer being treated for stab wounds is recovering at a hospital.
The unnamed 45-year-old attacker was shot dead by a police officer in the courtyard of the building.
The motive for the attack is not clear but investigators suspect a workplace dispute with bosses led to the incident.
The man had hearing disability. He converted to Islam 18 months ago.
Officers said the attacker was a model employee who never troubled anybody during his 20 years of administrative service.
According to police, the attacker suffered a moment of madness.
Police searched his home in a suburb of Paris and took his wife into custody.
Emery Siamandi, an employee, said officers were crying and running in panic amid a gun shot during lunchtime.
Ambulances arrived at the building located near the courthouse and Notre Dame Cathedral.
The nearby metro station, Cite, was closed as a security precaution.
An emergency message broadcast over loudspeakers from the courthouse said an attack had taken place at the police headquarters and the area was under surveillance.
Interior Minister Christophe Castaner postponed his trip to Turkey and visited the scene of attack.
Mayor Anne Hidalgo said Paris is praying for the friends and family of those killed.
The knife attack happened a day after a nationwide ‘March of Anger’ by officers who chanted slogans against long shifts and overtime while policing the year-long ‘yellow vest’ protests.
Some marchers carried coffins marked ‘52’ denoting the number of officers driven to suicide by their working conditions this year.
Police officers had already been stretched to the limit following a succession of terror attacks in France in the past four years leaving some 250 people dead.
In early 2015, two terrorists attacked the Paris offices of the satirical weekly Charlie Hebdo, killing 12 people.
On November 13 the same year, Islamic State terrorists killed 130 people in coordinated attacks on multiple locations in Paris.
On July 14, 2016 a Tunisian drove a truck through a crowd of revellers gathered for Bastille Day fireworks in Nice, killing 86 people.