Gunshots rang out as a group of Eritreans brawled with Afghans on the northern French coast.
Four people were critically injured in the shooting, including one who was blasted in the head, with another two also suffering bullet wounds.
A further 12 were left injured as the violence raged in front of stunned drivers and onlookers.
Some were said to be suffering from head injuries after being attacked with metal poles.
Police said they had to intervene to protect the Afghan migrants after they were “threatened by 200 migrants of Eritrean nationality”.
Authorities said there were two fights, one of which is thought to have lasted for around two hours.
Witnesses claimed some of those taking part were wielding clubs and iron bars.
A further clash took place on a nearby industrial estate as fighting brought chaos to the area.
French Interior Minister Gerard Collomb today said he would travel to Calais to review the situation following what he called today’s “serious incidents”.
He tweeted: “After the serious incidents that have occurred today, I am going to Calais tonight for a situation with the prefect, the mayor of the city and the local actors.
More than 100 illegal immigrants and 50 law enforcement were involved in that violent scuffle, which erupted after migrants tried to stop police from dismantling their newly-built camp and destroying their tents.
Three other migrants and two riot police officers were also injured in the clashes, during which rocks were hurled and tear gas was fired.
Calais remains a magnet for hundreds of young people determined to reach the UK.
Few have been deterred by French President Emmanuel Macron’s pledge to crack down on illegal immigration.
Authorities say around 600 migrants are in the Calais region, though humanitarian groups put the number at 800.