A KNIFE-WIELDING man who stabbed four police employees to death before being shot has been confirmed as an IT worker at police headquarters in Paris.

A fifth person was critically injured in the incident and was being treated in hospital after the deadliest attack on police in France in years. The motive of the attack remains unclear.

He killed three male officers and a female assistant before being shot in the courtyard of the square stone building next to the Notre-Dame cathedral in the historic heart of Paris.

The man, who was born in the French Caribbean territory of Martinique and had worked for the police since 2003, had a hearing disability.

Police searched his home in a quiet residence in Gonesse, a low-income suburb north of Paris, and took his wife into custody.

Interior Minister Christophe Castaner said the assailant had “never shown any behavioural problems”.

The police were “particularly stricken by this exceptionally grave incident”, said Castaner.

The assailant used a kitchen knife to stab the three policemen in their offices before going on to attack the female employee on the staircase. 

In the courtyard, he was confronted by an officer who ordered him to drop the knife. When he refused, the officer shot him in the head, police sources said.

Sources close to the investigation said the attacker, a 45-year-old IT worker in the police intelligence department, had converted to Islam 18 months ago.

Paris prosecutor Remy Heitz said he was “in constant contact” with anti-terrorism investigators about the case but that for the moment it was being handled by his office. 

The police building was cordoned off after the lunchtime attack in the centre of Paris and dozens of police and emergency vehicles converged at the scene.

Initial reports said investigators believed a workplace dispute could have sparked the incident.

“Did he snap, or was there some other reason? It’s still too early to say,” Loic Travers, head of the Alliance Police union for the Paris region, told BFM television.

Thursday’s killings comes amid growing tensions within the ranks of the police, who have been stretched to the limit after a year of trying to contain weekly “yellow vest” anti-Macron demonstrations.

Thousands of police officers marched in Paris Wednesday for better working conditions, a rare protest that took place against the backdrop of a spike in police suicides – 52 so far this year.

The police has been a recurring target of jihadist groups, such as Islamic State, behind a wave of attacks in France since 2015, from large synchronised assaults to isolated knife and gun attacks.

In January 2015, two police officers were among 12 people killed when gunmen stormed the Paris offices of satirical weekly Charlie Hebdo. A day later, a policewoman was shot dead in southern Paris.

In June 2016, a police couple were stabbed to death in their home in a suburb west of Paris by a man claiming allegiance to IS, who broadcast the attack live on Facebook.

And in April 2017, a man opened fire on a police van on the Champs-Elysees in Paris, killing an officer and wounding two others along with a pedestrian.