Three officers and an administrative assistant were stabbed to death at Paris police headquarters by an employee who went on a rampage after evading security with a ceramic knife.

The 45-year old, named by local media as Mickaël H, had worked for 20 years in the IT department of the police intelligence section in offices in Paris’ central île de la Cité, a stone’s throw from Notre Dame cathedral.

He was shot dead at the scene after killing three men and a woman.

Police sources said the assailant, who was partially deaf and reportedly converted to Islam 18 months ago, was "in conflict" with his superiors. Police last night said they had not determined a terror links.

Interior minister Christophe Castaner said the assailant had had "never shown any behavioural problems". The police were “struck to the heart” by the exceptionally grave incident, he added.

Three of the dead were police officers and the fourth was an administrative assistant. A fifth person who was critically injured was being treated in hospital.

Union official Loic Travers said the attack on Thursday appears to have begun in an office and continued elsewhere inside the large compound across the street from Notre Dame Cathedral.