A surge in refugee arrivals since Emmanuel Macron urged the United Kingdom to take in more unaccompanied minors last month has seen an already overwrought atmosphere riddled with tensions as displaced people hoped to be granted passage to Britain.
Interior Minister Gerard Collomb told reporters in Calais on Friday that five of the victims were injured by gunfire in Thursday's fighting, blaming migrant traffickers and "totally organized" gangs. In return, Theresa May agreed pay for more fencing, CCTV and detection devices, and to take in more unaccompanied minors.
The episode reached "a level of violence never seen before" in Calais, according to French Interior Minister Gérard Collomb, who arrived at the scene to oversee the government's response.
The notorious Jungle, once home to some 10,000 people, was demolished in 2016, but hundreds more migrants have since descended on the city.
Firearms are rare among migrants, and the shootings were the most serious clash in recent times among migrants around Calais.
The mainly Afghan and Eritrean gangs clashed soon after 3.30pm on Thursday as charity workers distributed meals close to the ferry port.
Shortly afterwards, over 100 Eritreans armed with iron rods and sticks attacked a group of around 20 Afghans at another food distribution point next to an industrial estate, prosecutors said.
However, humanitarian organizations say Europe's convoluted asylum process makes it almost impossible for people to get the help they need.
Further violence broke out in the late afternoon at a third site.
Another two migrants suffered less serious gunshot wounds and 12 others had other injuries, the local prefecture said, adding the numbers could change.
Aid organizations in Calais said that violent outbreaks would recur if the French government did not improve conditions for migrants stuck in legal limbo.
In July, 16 people were injured in a brawl, one seriously.
Macron has taken an unbending line towards those dubbed economic migrants because they are not fleeing war or persecution. This approach, he argued, would mix "humanity" with "efficiency".
Polls show the French supporting his approach but leftist parties, intellectuals and NGOs have been critical.