A 45-year-old IT assistant at the police headquarters in central Paris went on a knife rampage inside the building on Thursday, killing three police officers and an administrative worker before he was shot dead by an officer, French officials said.

His motive is currently unknown, according to Christophe Crépin, the spokesperson for the police union. Crépin added that the attacker entered the building at around 1p.m. local time.

However, police union officials are reported to have suggested the attacker may have been involved in a workplace dispute.

A murder investigation is said to have been launched.

An interpreter who was in the building during the attack, Emery Siamandi, said, "People were running everywhere, there was crying everywhere. 

"I heard a shot, I gathered it was inside. 

"Moments later, I saw police officers crying. They were in a panic."

Following the attack police cordoned off the surrounding area, as well as at least one metro station near the scene. 

French broadcaster BFM TV said the attacker had converted to Islam 18 months ago. 

The French Interior Minister, Christophe Castaner, cancelled his planned trip to Turkey to visit the scene of the attack. President Emmanuel Macron and the Prime Minister Édouard Philippe were also reportedly on scene.

In the past four years, the French capital has been rocked by violent attacks resulting in mass casualties. 

Coordinated bombings and shootings by Islamist militants in November 2015, at the Bataclan theater and other locations around Paris, killed 130 people in the deadliest attacks in France since World War II . 

In a three-day killing spree in January 2015, Islamist gunmen killed reporters and illustrators at satirical weekly Charlie Hebdo, police officers, and shoppers at a Jewish supermarket.