BBC News has contacted local authorities for comment.
Vergriete described the incident as a “tragedy” and said “an individual coldly murdered several people” in the area.
Xavier Bertrand, head of the region’s assembly, confirmed on X that five people had died in a “tragic event”.
French media reported a large emergency services presence close to a migrant camp, though it is unclear if the shootings took place inside a settlement.
Loon-Plage is home to several temporary settlements housing migrants. It is near to Calais and the Strait of Dover, which is the narrowest part of the Channel.
Similar camps along France’s northern coast have been used by people attempting to reach the UK via small boats.