A man who turned himself in saying he was responsible for five murders in northern France had no criminal record, authorities said Sunday.
The 22-year-old suspect was taken into custody on Saturday after surrendering at a police station in Ghyvelde just outside the Channel port city of Dunkirk around 5:20 pm (1620 GMT) on Saturday 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 -- several 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.
In the first incident, a 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 and a young father who ran a trucking company employing around 30 people.
"People in town are stunned," Wormhout mayor David Calcoen told AFP, adding that he hoped "the justice system will soon have information to decipher these unthinkable events".
Then at around 4:00 pm, 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, one known locally for working as bouncers at carnival events and the other as a volunteer at the local motorbike club.
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.
"We don't understand at all why two exiled people were targeted," said Salome Bahri of the Utopia 56 aid group.
She added that authorities have "planned nothing" to aid other camp residents with psychological support or shelter -- even though "many of them saw what happened".