LILLE, Dec 15 — A man who turned himself in saying he was responsible for five murders in northern France had no criminal record, authorities said today.

The 22-year-old suspect was taken into custody yesterday after surrendering at a police station in Ghyvelde just outside the Channel port city of Dunkirk around 5.20pm (1620 GMT/12.30am Malaysian time) yesterday afternoon — two hours after the first killing.

He is "unknown to the police service and judicial authorities,” Dunkirk’s chief prosecutor Charlotte Huet said in a statement.

A charge of murder combined with other crimes and possession of restricted firearms — five of which were found in the suspect’s car — carries a maximum sentence of life in jail.

"Many inquiries are underway,” prosecutor Huet said, especially "to clarify the reasons that led the suspect to commit these crimes”.

A source familiar with the case said police are investigating whether the man had a professional falling-out with the companies where the first three victims worked.

All five murders were committed within less than two hours in the Dunkirk area.

A first 29-year-old man was killed with several gunshots outside his house in Wormhout, a village just south of the city, prosecutors said.

The local town hall hailed the man as a local business owner who ran a trucking company.

Then at around 4pm, two security guards aged 33 and 37 were killed as they patrolled an industrial zone adjacent to the port in Loon-Plage, just west of Dunkirk.

Tributes were posted on Facebook to the two men, known locally for working as bouncers at carnival events.

Minutes later, still on the outskirts of Loon-Plage, two final victims believed to be Iranians aged 19 and 30 were shot dead.

Local police and the prefecture said the men were living in a local camp for migrants.

Many migrants hoping to reach Britain make their way to northern France before attempting perilous Channel crossings in small inflatable boats. — AFP