The beefed-up security adds to what was already a heavy law enforcement presence, with extra patrols in parts of the city that some 800 migrants still call home nearly 18 months after authorities dismantled the infamous "Jungle" migrant camp
Thursday's violence highlighted the growing tension in Calais, where migrants arriving in the wake of a deal struck last month between Britain and France
to speed up asylum processes have upset the delicate balance between migrant ethnic communities.
The result, according to aid groups, has been more intense competition for smugglers who charge as much as $3,700 (3,000 euros) per person to get migrants across the English Channel.
"I don't think that the refugees really understand the politics, but they heard a rumor that some might get to the UK, and with desperate people, any hope at all is something that they jump at," Clare Moseley of the charity aid group Care4Calais
French authorities have vowed not allow the development of another "Jungle"-style encampment, where some 7,000 migrants -- including 1,200 children -- lived in tents and shacks for two years before it was dismantled in 2016.
Since the migrant crisis peaked in 2015, European leaders have tried to limit the numbers of migrants making their way illegally through the continent. Though the numbers dropped -- 984,000 people were living without proper registration in the European Union in 2016, compared with 2.2 million in 2015, Eurostat reports
-- throngs continue to arrive in Europe from Africa, the Middle East and South Asia.
'Volunteers ... make Europe human'
By Saturday morning, migrants in Calais were once again lining up for breakfast provided by humanitarian organizations.
Ali, a 26-year-old man from eastern Ethiopia, explained that without them, the migrants would die.
"It is the volunteers that make Europe human," said Ali, who didn't want to give his last name for fear of arrest.
Ali, who arrived in Italy in July, said conditions have gotten worse lately, with the police taking down the migrants' tents every few days, leaving them with nothing but the hope that volunteers will bring them fresh ones. Calais police declined to comment on the claim.
With the migrants dependent on aid groups even for water, Calais has become hell on earth, Ali said.
Ali said he stays because he can't afford to pay smugglers to get him to Britain but also cannot go to refuges provided by the French authorities because of the so-called Dublin regulation,
a European Union law that requires asylum-seekers in most cases to apply in the first European country they enter.
Returning to Italy would leave him without shelter or hope, Ali said. And returning to Ethiopia is also out of the question because of the persecution he said he faces as a member of the Oromo ethnic minority.
Ali said it's been six months since he spoke with his wife or mother, adding that his father was killed in December.
All he wants now, Ali said, is shelter and, at last, to be treated as a human being.