Fierce clashes have broken out between migrants and riot police after the French authorities began to dismantle a camp known as "The Jungle".
One video posted online appeared to show people running away from clouds of tear gas, which was fired after up to 200 migrants and activists started to throw stones.
Multiple tents were also set on fire as demolition teams in high-visibility jackets attempted to tear down the makeshift homes.
The action came just days after a judge in Lille ruled that a partial clearance of the camp - excluding social spaces such as schools and places of worship - could go ahead.
French authorities want to relocate people from the squalid site to heated containers nearby or to centres around France.
British volunteers have condemned the French authorities for their handling of the demolition.
"We're very disappointed because the French interior minister Bernard Cazeneuve insisted in a public statement that the clearance would be done in a humane fashion," Tanya Freedman, of Help Refugees, said.
"On the first major day of dismantling, this is the way they are going about things."