Four migrants were taken into custody on Wednesday following a shooting Tuesday at the Grande-Synthe migrant camp near Dunkirk, in northern France.

Eric Fouard, Dunkirk's public prosecutor, told VICE News that the four people in custody were Iraqi Kurds who were injured in the shooting.

"We were informed last night that they were directly involved in the shooting," he said.

The shooting, he added, appeared to be a "settling of scores" between rival bands of smugglers. Investigators are still determining what set off the dispute. When contacted by VICE News Wednesday, a spokesperson for Grande-Synthe town hall characterized the shooting as an incident "between smugglers" and declined further comment on the situation.

Some 2,500 people — including hundreds of families — currently live in squalid conditions inside the camp in Grande-Synthe, which is built on a patch of marshland by the A16 motorway that connects Dunkirk to the port city of Calais. Dunkirk, which is a smaller port with less security than Calais, has been attracting migrants who are hoping to get to the UK by ferry.

The Grande-Synthe camp is seen as a strategic location by the people smugglers who operate around the port of Dunkirk and on a nearby service area. Aid workers have described the conditions in Grande-Synthe as far worse than those in Calais's infamous "Jungle" settlement — a precarious camp that houses nearly 5,000 migrants and refugees.

Shots rang out at the camp around 4:30pm on Tuesday, triggering a massive police intervention. Riot police were also dispatched to the scene, cordoning off the area and interrupting traffic in the neighboring area. Local residents were ordered to stay indoors.

Police and riot police moved into the camp around 6:30pm, carrying out searches to locate any weapons or suspects. "All the officers found were 9mm cartridges — five in total — that came from a handgun," said Fouard.

"By [Wednesday] morning, the situation was back to normal," a spokesperson for the medical charity Doctors Without Borders (MSF) told VICE News.

MSF is one of the only humanitarian aid groups with a regular presence in the slum — a sprawling tent city in a flood-prone area.

"Our teams were on site earlier this morning and they will carry on with their work as usual today," the spokesperson said, adding that riot police were stationed around the camp.

The vast majority of migrants living in the camp are Kurds who have fled conflict in Iraq and Syria, in the hope of reaching the UK. Many children also live in the cold, muddy camp, lacking the most basic of comforts.

VICE News visited the camp earlier this month, shortly after local authorities announced plans to build a semi-permanent settlement to re-house 2,500 migrants in the area. Officially approved by the government on January 20, the new camp will feature heated tents and temporary structures housing bathrooms.

Construction of the new camp is "on the right track," according to MSF. "Preparing the site is taking a long time, but we think we should be able to set up the first tents soon," the spokesperson told VICE News.

In a statement released Wednesday, the Grande-Synthe Town Hall said that, once migrants had been relocated, the current camp would be destroyed. The new camp, it said, was not intended to be a permanent structure, and any spaces freed up by migrants would "not be filled."

Tuesday's shooting is the latest in a string of incidents at the camp in the last six months. In June 2014, a migrant was shot in the legs by someone firing a weapon from a car. In September, several car chases between the police and suspected smugglers and rising tensions within the camp had led to several raids inside the settlement.

Follow Pierre-Louis Caron on Twitter: @pierrelouis_c